Which AI model is best for reasoning in 2026?

Gemini 3.1 Pro leads reasoning benchmarks in February 2026, scoring 94.3% on GPQA Diamond, 77.1% on ARC-AGI-2, and 44.4% on Humanity's Last Exam without tools. Claude Opus 4.6 leads agentic reasoning tasks requiring tools, scoring 53.0% on HLE with Tools.

Which frontier AI model has the largest context window?

Grok 4.1 has the largest standard context window at 2 million tokens as of February 2026. Gemini 3.1 Pro offers 1 million tokens as standard. Claude Opus 4.6 and Sonnet 4.6 support 200K tokens with 1 million in beta.

What is the cheapest frontier AI model in 2026?

DeepSeek V3.2 is the cheapest at $0.28 per million input tokens and $0.42 per million output tokens as of February 2026. Among proprietary models, Grok 4.1 is most affordable at $0.20 per million input and $0.50 per million output.

Which AI model is fastest in 2026?

Grok 4.1 is the fastest frontier model at 118 tokens per second as of February 2026. Gemini 3.1 Pro is second at 91 to 110 tokens per second. Claude Opus 4.6 outputs at 67 to 72 tokens per second.

Is DeepSeek V3.2 open source?

Yes. DeepSeek V3.2 is the only fully open-weight frontier model in this comparison, released under an MIT license. It can be self-hosted on your own infrastructure.

How does Claude Opus 4.6 compare to GPT-5.3 Codex?

Claude Opus 4.6 and GPT-5.3 Codex score nearly identically on SWE-bench Verified: 80.8% vs 80.0%. Opus 4.6 leads on computer-use, agentic tasks, and human preference. GPT-5.3 Codex leads on autonomous coding and math. Opus 4.6 costs $25 per million output tokens versus approximately $14 for GPT-5.3.

Frontier AI Model Report

February 2026

A comprehensive benchmark analysis for executives, founders and operators

Claude Opus 4.6

Claude Sonnet 4.6

Gemini 3.1 Pro

GPT-5.3 Codex

Grok 4.1

DeepSeek V3.2

What This Report Covers

Side-by-side benchmark results for 6 frontier AI models across reasoning, coding, agentic tasks, multimodal, long context, price, and speed. Sourced from official model cards and third-party evaluations as of February 27, 2026.

Bottom Line

No single model wins every category. Gemini 3.1 Pro leads reasoning. GPT-5.3 Codex leads autonomous coding. Claude Opus 4.6 leads agentic and computer-use tasks. Grok 4.1 leads speed and context. DeepSeek V3.2 leads cost and open-source access.

Quick Answers

Best for reasoning

Gemini 3.1 Pro

94.3% GPQA Diamond

Best for coding

GPT-5.3 Codex

77.3% Terminal-Bench 2.0

Best for agentic tasks

Claude Opus 4.6

53.0% HLE with Tools

Best value

DeepSeek V3.2

$0.28/M input tokens

Section 01

Which AI Model Has the Best Reasoning?

Gemini 3.1 Pro leads PhD-level and abstract reasoning in February 2026, scoring highest on GPQA Diamond (94.3%), ARC-AGI-2 (77.1%), and Humanity's Last Exam without tools (44.4%). Claude Opus 4.6 leads when tools are available, scoring 53.0% on HLE with Tools.

GPQA Diamond (PhD-level science)

Opus 4.6

91.3%

Sonnet 4.6

74.1%

Gemini 3.1

94.3 ★

GPT-5.3

92.4%

Grok 4.1

87.5%

DeepSeek

79.9%

ARC-AGI-2 (novel abstract reasoning)

Opus 4.6

68.8%

Sonnet 4.6

60.4%

Gemini 3.1

77.1 ★

GPT-5.3

52.9%

Grok 4.1

N/R

DeepSeek

N/R

Humanity's Last Exam (no tools)

Opus 4.6

40%

Sonnet 4.6

19.1%

Gemini 3.1

44.4 ★

GPT-5.3

34.5%

Grok 4.1

25.4%

DeepSeek

N/A

HLE with Tools

Opus 4.6

53 ★

Sonnet 4.6

N/A

Gemini 3.1

51.4%

GPT-5.3

45.5%

Grok 4.1

N/A

DeepSeek

N/A

AIME 2025 (competition math)

Opus 4.6

~82%

Sonnet 4.6

~70%

Gemini 3.1

95%

GPT-5.3

100 ★

Grok 4.1

~95%

DeepSeek

96%

MMMLU (multilingual knowledge)

Opus 4.6

91.1%

Sonnet 4.6

79.1%

Gemini 3.1

92.6 ★

GPT-5.3

89.6%

Grok 4.1

N/A

DeepSeek

N/A

Section 02

Which AI Model is Best for Coding and Software Engineering?

GPT-5.3 Codex leads autonomous coding with 77.3% on Terminal-Bench 2.0, 56.8% on SWE-bench Pro, and a perfect 100% on AIME 2025. Claude Opus 4.6 leads computer-use with 72.7% on OSWorld-Verified. Gemini 3.1 Pro leads competitive programming at 75.6% on LiveCodeBench.

SWE-bench Verified (real GitHub bugs)

Opus 4.6

80.8 ★

Sonnet 4.6

79.6%

Gemini 3.1

80.6%

GPT-5.3

~80%

Grok 4.1

~75%

DeepSeek

67.8%

SWE-bench Pro (harder tasks)

Opus 4.6

N/A

Sonnet 4.6

N/A

Gemini 3.1

54.2%

GPT-5.3

56.8 ★

Grok 4.1

N/A

DeepSeek

N/A

Terminal-Bench 2.0 (agentic terminal)

Opus 4.6

65.4%

Sonnet 4.6

59.1%

Gemini 3.1

68.5%

GPT-5.3

77.3 ★

Grok 4.1

N/R

DeepSeek

31.3%

OSWorld-Verified (computer-use agent)

Opus 4.6

72.7 ★

Sonnet 4.6

72.5%

Gemini 3.1

N/R

GPT-5.3

64.7%

Grok 4.1

N/R

DeepSeek

N/R

LiveCodeBench (competitive programming)

Opus 4.6

~62%

Sonnet 4.6

~58%

Gemini 3.1

75.6 ★

GPT-5.3

~65%

Grok 4.1

~63%

DeepSeek

74.1%

Section 03

Which AI Model is Best for Agentic Tasks and Tool Use?

Claude Sonnet 4.6 leads office productivity with a GDPval-AA Elo of 1,633. Claude Opus 4.6 leads customer service agent tasks (93.5%) and finance agent benchmarks (60.7%). Gemini 3.1 Pro leads general web research at 85.9% on BrowseComp.

GDPval-AA Elo bars normalized to 1,700 max.

tau2-bench Retail (customer service agent)

Opus 4.6

93.5 ★

Sonnet 4.6

91.7%

Gemini 3.1

90.8%

GPT-5.3

82%

Grok 4.1

N/A

DeepSeek

N/A

GDPval-AA Elo (office productivity)

Opus 4.6

1,606

Sonnet 4.6

1,633 ★

Gemini 3.1

1,317

GPT-5.3

1,462

Grok 4.1

N/A

DeepSeek

N/A

BrowseComp (web research agent)

Opus 4.6

84%

Sonnet 4.6

N/A

Gemini 3.1

85.9 ★

GPT-5.3

65.8%

Grok 4.1

N/A

DeepSeek

N/A

Finance Agent

Opus 4.6

60.7%

Sonnet 4.6

63.3 ★

Gemini 3.1

N/A

GPT-5.3

N/A

Grok 4.1

N/A

DeepSeek

N/A

Section 04

Which AI Model Has the Best Multimodal and Long Context Support?

Gemini 3.1 Pro leads vision and reasoning at 80.5% on MMMU-Pro. Claude Opus 4.6 and Gemini 3.1 Pro tie for 128K long-context retrieval at 84.9%. Claude Opus 4.6 leads extreme 1-million-token context at 76.0%. DeepSeek V3.2 is text-only with no vision support.

MMMU-Pro (vision + reasoning)

Opus 4.6

73.9%

Sonnet 4.6

~68%

Gemini 3.1

80.5 ★

GPT-5.3

79.5%

Grok 4.1

N/A

DeepSeek

text-only

MRCR v2 128K (long-context retrieval)

Opus 4.6

84.9 ★

Sonnet 4.6

~81%

Gemini 3.1

84.9 ★

GPT-5.3

83.8%

Grok 4.1

N/A

DeepSeek

N/A

MRCR v2 1M tokens (extreme long context)

Opus 4.6

76 ★

Sonnet 4.6

N/A

Gemini 3.1

26.3†

GPT-5.3

N/A

Grok 4.1

N/A

DeepSeek

N/A

Section 05

Context Windows, API Access, and Release Dates

Full specifications for all six frontier models as of February 2026, including pricing, output speed, context window size, and the Artificial Analysis Intelligence Index composite score.

	Claude Opus 4.6	Claude Sonnet 4.6	Gemini 3.1 Pro	GPT-5.3 Codex	Grok 4.1	DeepSeek V3.2
Released	Feb 5 '26	Feb 17 '26	Feb 19 '26	Feb 5 '26	Nov 17 '25	Dec 1 '25
Context Window	200K (1Mβ)	200K (1Mβ)	1M std	~200K	2M	128K
Input $/1M tokens	$5.00	$3.00	$2.00	~$1.75	$0.20	$0.28
Output $/1M tokens	$25.00	$15.00	$12.00	~$14.00	$0.50	$0.42
Speed (tokens/sec)	67-72	54-56	91-110	~89	118	49
Arena Elo	~1,506 #1	Top 5	~1,492	Testing	~1,483	N/R
AA Intelligence Index	53	52	57	N/R	35†	32
Open weights	No	No	No	No	No	MIT ✓

Section 06

Which Frontier AI Model Offers the Best Value?

Output cost and inference speed determine which model is practical at scale. Grok 4.1 leads speed at 118 tokens per second. DeepSeek V3.2 leads cost at $0.42 per million output tokens.

Output Price: $/1M Tokens

Opus 4.6

$25.00

Sonnet 4.6

$15.00

Gemini 3.1

$12.00

GPT-5.3

$14.00

Grok 4.1

$0.50

DeepSeek

$0.42

Speed: Tokens per Second

Opus 4.6

67-72 t/s

Sonnet 4.6

54-56 t/s

Gemini 3.1

91-110 t/s

GPT-5.3

~89 t/s

Grok 4.1

118 t/s

DeepSeek

49 t/s

Section 07

Where Each Model Wins

Claude Opus 4.6

Best for complex agentic work

→OSWorld computer-use leader (72.7%)
→HLE with Tools leader (53.0%)
→tau2-bench Retail (93.5%)
→Arena Elo #1 (~1,506)
→1M-token long context (76.0%)
→Human preference overall

Claude Sonnet 4.6

Best production value

→Office work Elo #1 (1,633)
→Finance agent leader (63.3%)
→Near-Opus quality at 60% cost
→79.6% SWE-bench Verified

Gemini 3.1 Pro

Best reasoning + price-performance

→ARC-AGI-2 leader (77.1%)
→GPQA Diamond leader (94.3%)
→HLE no-tools leader (44.4%)
→AA Intelligence Index #1 (57)
→Fastest major model (91-110 t/s)
→1M context standard

GPT-5.3 Codex

Best autonomous coding

→Terminal-Bench 2.0 leader (77.3%)
→SWE-bench Pro leader (56.8%)
→AIME 2025 perfect score (100%)
→FrontierMath Tiers 1-3 (40.3%)

Grok 4.1

Best speed + value

→Fastest output (118 t/s)
→Largest context window (2M tokens)
→EQ-Bench #1 (1,586)
→Built-in real-time X/web search
→$0.50/M output: 50x cheaper than Opus

DeepSeek V3.2

Best open-source

→Only fully open-weight model (MIT)
→AIME 2025 (96.0%)
→LiveCodeBench (74.1%)
→$0.42/M output: cheapest API
→Self-hostable on your own infrastructure

Original Analysis

Price-Performance Index

Attainment's Price-Performance Index divides each model's AA Intelligence Index score by its output cost per million tokens. Higher is better. GPT-5.3 Codex is excluded: no AA Intelligence Index score is published as of this report.

Model	AA Index	Output $/1M	Price-Performance
DeepSeek V3.2	32	$0.42	76.2 pts/$
Grok 4.1	35	$0.50	70.0 pts/$
Gemini 3.1 Pro	57	$12.00	4.8 pts/$
Claude Sonnet 4.6	52	$15.00	3.5 pts/$
Claude Opus 4.6	53	$25.00	2.1 pts/$
GPT-5.3 Codex	N/A	$14.00	N/A

Price-Performance = AA Intelligence Index divided by output cost per million tokens. Higher score means more intelligence per dollar. Calculated by Attainment, February 2026.

Methodology

How We Scored These Models

Benchmark scores were collected from official model cards, provider documentation, and independent evaluation platforms. All data reflects published results as of February 27, 2026. We selected benchmarks that measure distinct capabilities: PhD-level science knowledge (GPQA Diamond), abstract reasoning (ARC-AGI-2), real-world software engineering (SWE-bench), autonomous computing (OSWorld), and vision reasoning (MMMU-Pro). The AA Intelligence Index from Artificial Analysis provides a composite score normalized across evaluations.

Primary Sources

GPQA Diamond (Google DeepMind)
ARC-AGI-2 (ARC Prize Foundation)
Humanity's Last Exam (MATS Research)
SWE-bench (Princeton NLP)
OSWorld (OSWorld Benchmark)
MMMU-Pro (MMMU Benchmark)
LMSYS Chatbot Arena (LMSYS)
Artificial Analysis Intelligence Index (Artificial Analysis)

Summary

Key Takeaways

1
Gemini 3.1 Pro: Gemini 3.1 Pro leads raw reasoning: GPQA Diamond 94.3%, ARC-AGI-2 77.1%, AA Intelligence Index 57. Best reasoning-per-dollar of any frontier model in this report.
2
Claude Opus 4.6: Claude Opus 4.6 ranks highest by human preference (Arena Elo ~1,506) and leads agentic benchmarks: OSWorld 72.7%, HLE with Tools 53.0%, tau2-bench Retail 93.5%.
3
GPT-5.3 Codex: GPT-5.3 Codex leads autonomous coding: Terminal-Bench 2.0 at 77.3%, SWE-bench Pro at 56.8%, and a perfect 100% on AIME 2025 math.
4
Claude Sonnet 4.6: Claude Sonnet 4.6 is the best production value: leads office workflow Elo (1,633) and finance agent tasks (63.3%) at 60% of Claude Opus pricing.
5
Grok 4.1: Grok 4.1 is the fastest model (118 tokens per second) with the largest context window (2M tokens) and output pricing of $0.50/M: 50x cheaper than Claude Opus 4.6.
6
DeepSeek V3.2: DeepSeek V3.2 is the only MIT-licensed open-weight model, with competitive coding scores (LiveCodeBench 74.1%) and the cheapest API at $0.42/M output.

FAQ

Frequently Asked Questions

Which AI model is best for reasoning in 2026?: Gemini 3.1 Pro leads reasoning benchmarks in February 2026, scoring 94.3% on GPQA Diamond, 77.1% on ARC-AGI-2, and 44.4% on Humanity's Last Exam without tools. Claude Opus 4.6 leads agentic reasoning tasks requiring tools, scoring 53.0% on HLE with Tools.
Which AI model is best for coding in 2026?: GPT-5.3 Codex leads autonomous coding benchmarks in February 2026, scoring 77.3% on Terminal-Bench 2.0, 56.8% on SWE-bench Pro, and a perfect 100% on AIME 2025. Claude Opus 4.6 leads computer-use tasks with 72.7% on OSWorld-Verified.
Which frontier AI model has the largest context window?: Grok 4.1 has the largest standard context window at 2 million tokens as of February 2026. Gemini 3.1 Pro offers 1 million tokens as standard. Claude Opus 4.6 and Sonnet 4.6 support 200K tokens with 1 million in beta.
What is the cheapest frontier AI model in 2026?: DeepSeek V3.2 is the cheapest at $0.28 per million input tokens and $0.42 per million output tokens as of February 2026. Among proprietary models, Grok 4.1 is most affordable at $0.20 per million input and $0.50 per million output.
Which AI model is fastest in 2026?: Grok 4.1 is the fastest frontier model at 118 tokens per second as of February 2026. Gemini 3.1 Pro is second at 91 to 110 tokens per second. Claude Opus 4.6 outputs at 67 to 72 tokens per second.
Is DeepSeek V3.2 open source?: Yes. DeepSeek V3.2 is the only fully open-weight frontier model in this comparison, released under an MIT license. It can be self-hosted on your own infrastructure.
How does Claude Opus 4.6 compare to GPT-5.3 Codex?: Claude Opus 4.6 and GPT-5.3 Codex score nearly identically on SWE-bench Verified: 80.8% vs 80.0%. Opus 4.6 leads on computer-use, agentic tasks, and human preference. GPT-5.3 Codex leads on autonomous coding and math. Opus 4.6 costs $25 per million output tokens versus approximately $14 for GPT-5.3.

David Cyrus

Founder, Attainment

LinkedIn·About

Attainment is an AI-powered growth and operations firm based in Toronto. This report is produced independently with no paid placement or model provider sponsorship. All benchmark data is sourced from official model cards and third-party evaluations as of February 27, 2026.

Published February 27, 2026

† Gemini MRCR 1M uses a different evaluation variant. † Grok 4.1 AA Index is for the Fast (Reasoning) variant.

N/R = not run. N/A = not applicable. ~ = estimated. ★ = category leader.

Sources: Anthropic, Google DeepMind, OpenAI, xAI, DeepSeek model cards; Artificial Analysis Intelligence Index v4.0; LMSYS Chatbot Arena; Vals AI; Digital Applied LLM Comparison. All scores as of Feb 27, 2026.