Claude Sonnet 4.5 vs Qwen3.5-27B

Pick Claude Sonnet 4.5 if you want the stronger benchmark profile. Qwen3.5-27B only becomes the better choice if reasoning is the priority or you want the cheaper token bill.

Claude Sonnet 4.5 has the cleaner provisional overall profile here, landing at 68 versus 66. It is a real lead, but still close enough that category-level strengths matter more than the headline number.

Claude Sonnet 4.5's sharpest advantage is in coding, where it averages 77.2 against 72.4. The single biggest benchmark swing on the page is Terminal-Bench 2.0, 50% to 41.6%. Qwen3.5-27B does hit back in reasoning, so the answer changes if that is the part of the workload you care about most.

Claude Sonnet 4.5 is also the more expensive model on tokens at $3.00 input / $15.00 output per 1M tokens, versus $0.00 input / $0.00 output per 1M tokens for Qwen3.5-27B. That is roughly Infinityx on output cost alone. Qwen3.5-27B is the reasoning model in the pair, while Claude Sonnet 4.5 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. Qwen3.5-27B gives you the larger context window at 262K, compared with 200K for Claude Sonnet 4.5.