Best AI Coding Agents in 2026: Claude Code vs Codex vs Antigravity vs Muse Code

Four companies now want to live in your terminal: Anthropic, OpenAI, Google, and — as of three weeks ago — Meta. They all do roughly the same thing. They are not remotely the same product.

I compared Claude Code, OpenAI Codex, Google Antigravity, and Meta's brand-new Muse Code on the numbers that matter: benchmark scores, speed, price, and the stuff benchmarks miss. Here's who should use what.

Four labs, four agents, one terminal. Choose carefully.

The field at a glance

A note on reading that table honestly: every lab cherry-picks the benchmark where it wins. Anthropic quotes SWE-bench, OpenAI quotes Terminal-Bench, Google quotes throughput. The numbers above are real, but no single one settles the argument — which is why the rest of this article is about fit, not a trophy.

Claude Code: the quality pick

On hard, multi-file tasks, Claude Code is still the one to beat. The 64.3% vs 55.1% gap over Antigravity on SWE-Bench Pro is the difference between an agent that finishes a gnarly refactor and one that leaves you a half-done branch. It's slower (67 tok/s) and it costs money, but if you bill by the hour, wrong code is the most expensive thing an agent can produce.

The honest downside: on a big monorepo you'll feel the 200K context limit against Antigravity's 1M, and heavy daily use can push you past the $20 entry tier.

Antigravity: the speed-and-free pick

Google's agent is 4x faster, ships desktop + CLI + SDK, defaults to Gemini 3.5 Flash, and costs nothing during public preview. For prototyping, scripts, and everyday tasks, that combination is very hard to argue with. Where it stumbles is exactly where you'd expect: the hardest tasks, where its accuracy trails Claude Code by nine points. Free preview also means the pricing shoe hasn't dropped yet.

Codex: the ecosystem pick

Codex's pitch isn't a benchmark, it's convenience: if you already pay for ChatGPT, the agent is bundled into the subscription you have. GPT-5.5's 82.7% on Terminal-Bench 2.0 is a genuinely strong terminal-work score, and OpenAI's recent aggressive price cuts keep making the underlying API cheaper for anything you build yourself.

Muse Code: the wildcard

Meta's entry is three weeks old, free, and improving on a visible weekly cadence. It runs on Muse Spark 1.2 and hasn't published head-to-head numbers against the leaders, which tells you something by itself. But free is free, and Meta also open-sourced Muse Glimmer, a 30B agent model you can run on your own GPU — a self-hosted option none of the other three offers. Full thoughts in our Muse Code review.

Which one should you pick?

FAQ

One last thing: this market reprices monthly. Antigravity will eventually charge, Muse Code will eventually benchmark, and the price war keeps dragging everyone's costs down. Whatever you pick, re-evaluate in a quarter. In 2026, loyalty to a coding agent is just leaving capability on the table.