ChatGPT vs Claude vs Gemini vs Grok

OpenAI's ChatGPT remains the most widely-used AI assistant in the world. GPT-5.5 (April 23, 2026) takes #1 on the Artificial Analysis Intelligence Index with a score of 60, three points ahead of Claude Opus 4.7 and Gemini 3.1 Pro at 57. It dominates shell automation (Terminal-Bench 2.0: 82.7%, +13 over Opus 4.7) and advanced math (FrontierMath Tier 4: 35.4%). API pricing doubled vs 5.4 to $5/$30 per million tokens; a new GPT-5.5 Pro variant for longer reasoning sits at $30/$180. Codex now has a 1M-token context window with optional fast-mode at 2.5x cost. Honest caveats: GPT-5.5 still loses SWE-Bench Pro to Claude Opus 4.7 (58.6% vs 64.3%), loses MCP Atlas tool-use to both Opus (79.1%) and Gemini (78.2%), and posts an 86% hallucination rate on AA-Omniscience. The ecosystem advantage remains unmatched: DALL-E, Codex, Atlas browser, 60+ connectors, Memory, Projects, GPT Store, and Microsoft 365 Copilot integration. Sora video app/API is being discontinued (web/app April 26, 2026; API September 24, 2026).

Anthropic's Claude Opus 4.7 (April 16, 2026) still leads production coding with 87.6% on SWE-bench Verified and 64.3% on SWE-bench Pro, beating GPT-5.5 (58.6%) and Gemini 3.1 Pro despite GPT-5.5's broader Intelligence Index lead. Anthropic also wins MCP Atlas tool-use at 79.1%. Anthropic surpassed OpenAI in enterprise revenue in 2026 ($30B vs $25B annualized). The ecosystem expanded dramatically in April 2026: Claude Design (Anthropic Labs, April 17) for visual work tied to your codebase, Claude Code Routines (April 16) for cloud-hosted automation with schedule/webhook/GitHub triggers, a full desktop redesign (April 14) with parallel agent sessions and git worktree isolation, Claude Cowork GA on macOS and Windows, Agent Skills as an open standard with 1,000+ ready-made skills, and Computer Use in research preview. The 1M-token context window is now at standard API pricing with no long-context premium.

Google's Gemini 3.5 Flash (May 19, 2026) is the new headline model: a Flash-tier model that beats last generation's flagship 3.1 Pro on coding and agentic work. It posts 76.2% on Terminal-Bench 2.1, 83.6% on MCP Atlas tool-use, and 1656 Elo on GDPval-AA, while running ~280 tokens/sec (one of the fastest models measured) at $1.50/$9.00 per million tokens. On the Artificial Analysis Intelligence Index it scores 55, behind GPT-5.5 (60) and Claude Opus 4.7 (57) but sitting on the speed-intelligence frontier. Honest caveat: 3.1 Pro still wins the hardest abstract-reasoning tests (ARC-AGI-2, Humanity's Last Exam), and 3.5 Flash costs 3x the previous Gemini 3 Flash. Native multimodal across text, image, audio, and video with 1M-token context. Gemini 3.5 Pro is slated for next month. Deep integration across Google Workspace, NotebookLM, Veo 3.1, and the new Google Antigravity 2.0 agent platform.

xAI's Grok 4.20 (March 2026) ships in three variants: standard reasoning, non-reasoning, and a dedicated multi-agent version where Grok coordinates with Harper (research), Benjamin (logic/math), and Lucas (contrarian) running in parallel. Grok 4 Heavy was the first model to break 50% on Humanity's Last Exam (50.7%), and Grok 4.20 holds an industry-lowest 22% hallucination rate on the AA-Omniscience benchmark (beating Claude 4.5 Haiku, MiniMax V2 Pro, and GLM-5). xAI merged with SpaceX in February 2026 (combined valuation $1.25T) to pursue orbital data centers. The lineup includes grok-4.20-0309 (flagship, $2/$6 per M), grok-4.20-multi-agent-0309 (multi-agent version), grok-4-1-fast (2M context, $0.20/$0.50 per M tokens), grok-code-fast-1 for agentic coding, and Grok Imagine for image + video. Grok 5 is in training on Colossus 2, expected Q2/Q3 2026.