Verdict
Built from the measurements below
- Accuracy is too close to call: Claude Sonnet 5.5 scored 78.8% and Grok 4.7 80.0% on the same 80 questions, a gap within what chance alone could produce.
- Claude Sonnet 5.5 is 4.6× cheaper per question as billed ($0.0054 vs $0.025), reasoning tokens included.
- Claude Sonnet 5.5 generates text 1.6× faster: 126 tokens per second against 77.
- Claude Sonnet 5.5 starts answering sooner: 0.7 s to the first token, against 1.9 s for Grok 4.7.
- Claude Sonnet 5.5 accepts more context: 1M tokens against 500k.
Which should you choose?
Choose Claude Sonnet 5.5 for the lower cost per correct answer ($0.0069 against $0.031), faster streaming, a quicker first token, shorter outputs (about 456 tokens per question against 3,952), a 1M-token context window and more hosts to choose from on OpenRouter (5 against 1).
Accuracy gap -1.3 points (z = -0.20). We call a winner only when z is at least 1.96, the usual 95% threshold. Speed, latency and price need a 10% margin.