Claude Sonnet 4.6 vs Kimi K2.5 (Reasoning)

Pick Claude Sonnet 4.6 if you want the stronger benchmark profile. Kimi K2.5 (Reasoning) only becomes the better choice if knowledge is the priority or you want the cheaper token bill.

Claude Sonnet 4.6 is clearly ahead on the provisional aggregate, 83 to 76. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.

Claude Sonnet 4.6's sharpest advantage is in agentic, where it averages 65.1 against 54.6. The single biggest benchmark swing on the page is Terminal-Bench 2.0, 59.1% to 50.8%. Kimi K2.5 (Reasoning) does hit back in knowledge, so the answer changes if that is the part of the workload you care about most.

Claude Sonnet 4.6 is also the more expensive model on tokens at $3.00 input / $15.00 output per 1M tokens, versus $0.60 input / $3.00 output per 1M tokens for Kimi K2.5 (Reasoning). That is roughly 5.0x on output cost alone. Kimi K2.5 (Reasoning) is the reasoning model in the pair, while Claude Sonnet 4.6 is not. That usually helps on harder chain-of-thought-heavy tests, but it can also mean more latency and more token spend in real use. Claude Sonnet 4.6 gives you the larger context window at 200K, compared with 128K for Kimi K2.5 (Reasoning).