Best AI for Coding: Opus 5.5 vs Gemini 4 Carbon vs GPT-6 Astra

By GameDrop Staff · Nov 06, 2026 · Versus · 2 min read

Editorial illustration of AI model news — Image: The AI / news

Which AI model is best for coding in November 2026? On published numbers, Claude Opus 5.5 leads agentic coding and real-world task cost-effectiveness is a close fight, while Gemini 4 Carbon tops general intelligence by one point and GPT-6 Astra wins a few specific tests. Every figure below comes from third-party benchmark trackers or vendor tables, and we ran none ourselves.

Quick summary

Best for coding agents: Claude Opus 5.5 (Coding Agent Index 62 via Claude Code vs 59 for Carbon via Antigravity CLI).
Best overall score: Gemini 4 Carbon, 59 on the Artificial Analysis Intelligence Index v5 vs 58 (Opus) and 57 (Astra).
Best value on work tasks: Carbon, about $16 per GDPx task vs about $51 for Opus.
Astra is the priciest per token and wins FrontierSWE 2.

How do the three score side by side?

Benchmark	Gemini 4 Carbon	Claude Opus 5.5	GPT-6 Astra
AA Intelligence Index v5	59	58	57
Vals Index v2.2	70.4%	70.2%	65.0%
FrontierSWE 2	61.2%	62.3%	65.5%
Terminal-Bench 4.0	65.2%	59.6%	59.1%
OSWorld-2.1 (offline subset)	81.5%	87.2%	80.9%
AutomationBench (Zapier)	53.9%	42.5%	41.4%
GraphWalks 256K-1M	96.2%	66.8%	71.8%

Most of the Carbon column comes from Google's own launch table, so treat it as vendor-reported. The Intelligence Index figures are from Artificial Analysis.

Which AI is best for coding?

It depends on the test. On the Artificial Analysis Coding Agent Index, Opus 5.5 running in Claude Code scores 62 and Carbon in Antigravity CLI scores 59. On FrontierCode v1.1 Opus has 56% to Carbon's 51%. Carbon wins Terminal-Bench 4.0, and Astra wins FrontierSWE 2. Because each score also reflects the agent harness, a benchmark number is not a pure model comparison.

Our read: Opus 5.5 is the safer pick for repository-level agent work, Carbon is strong for terminal tasks, and Astra is competitive but costs more.

Which is best for office and work tasks?

On the GDPx benchmark of long professional tasks, Opus 5.5 scores 12.0% at $51.41 per task, Carbon 10.9% at $16.29 and Astra 9.6% at $53.99. That means Carbon delivers roughly 91% of Opus's score at about a third of the cost, though all three fail most tasks. Details in our GDPx explainer. On Zapier's AutomationBench, Carbon leads clearly.

How much do they cost?

An AI Agent Store comparison lists Opus 5.5 at $4 input and $20 output per million tokens, and Astra at $10 and $50. Google has applied a launch discount to Carbon that, per DEV Community's analysis, has no announced end date, so check current pricing before committing. Our Carbon explainer covers access.

What about hallucinations?

TBreak reports Carbon's AA-Omniscience hallucination rate at 11%, against 50% for both Opus 5.5 and Astra. If you need an assistant that admits uncertainty, that is a real point for Carbon, although it was not publicly available yet at that report.