The Leaderboard
On the Artificial Analysis Intelligence Index — a composite of reasoning, coding, math and knowledge benchmarks — the top of the table looks like this:
Note the spread: just over 8 points separate #1 from #4. For most real tasks, all four are extremely capable and the practical difference is small. (Claude Fable 5 would top this list outright — but it was pulled after a US export-control order on June 12, so it's not a model you can actually deploy right now.)
Best for Coding: Claude Opus 4.8
Opus 4.8 is the strongest generally available model for software engineering and long-running agentic coding tasks. It leads SWE-bench and holds up across multi-file refactors and debugging sessions where weaker models lose the thread.
| Model | SWE-bench Verified | SWE-bench Pro |
|---|---|---|
| Claude Opus 4.8 | 88.6% | 69.2% |
| GPT-5.5 | — | 58.6% |
| Gemini 3.1 Pro | — | 54.2% |
If you write code with AI daily, this is the default. For the heaviest agentic work — large migrations, hours-long autonomous runs — Fable 5 was briefly ahead, but Opus 4.8 is the reliable, available choice.
Best for Reasoning: Gemini 3.1 Pro
When the task is hardest-mode reasoning — graduate-level science, novel logic puzzles, memorization-proof problems — Gemini 3.1 Pro leads the published benchmarks:
- GPQA Diamond: 94.3% — graduate-level science reasoning
- ARC-AGI-2: 77.1% — novel, memorization-proof reasoning
If your work lives in research, hard math, or analysis where being wrong is expensive, Gemini 3.1 Pro is worth keeping in the rotation specifically for the hard cases.
Best for Writing: GPT-5.5
The GPT line has owned creative writing since GPT-5.1, and GPT-5.5 continues it with a warm, natural tone that still reads least like a machine. It launched on April 23, 2026 with a reported 60% drop in hallucinations versus GPT-5.4 — a meaningful reliability gain on top of its prose strengths. It's free in ChatGPT, or $5 / $30 per million tokens via API.
Best for Price-Performance: Gemini 3.5 Flash
Not every task needs a frontier brain. Gemini 3.5 Flash lands at an Intelligence Index of 55 — within striking distance of the top — at a fraction of the cost, making it the best value for high-volume work: classification, summarization, extraction, routing, and the cheap legs of an agentic pipeline.
The Quick-Pick Table
| If your job is… | Use | Why |
|---|---|---|
| Daily coding & agents | Opus 4.8 | Best available SWE-bench, reliable long runs |
| Hardest reasoning | Gemini 3.1 Pro | Leads GPQA & ARC-AGI-2 |
| Writing & natural tone | GPT-5.5 | Best prose, fewer hallucinations |
| High-volume / cheap | Gemini 3.5 Flash | Frontier-ish at a fraction of the price |
| Real-time / X data | Grok 4.3 | Strong all-rounder, live data access |
The Bottom Line
The frontier is a near-tie. Smartness is no longer the differentiator — fit is. Pick by task, not by leaderboard position, and keep at least two models wired up so you can switch when one gets better, cheaper, or (as June proved) suddenly unavailable.
Want to go deeper? Compare the same prompt across models with our multi-model workflow guide, explore live numbers in the AI Benchmarks tool, or let the AI Model Selector pick for your exact use case.
Use three models? Keep one prompt library.
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