GPT-5.4 vs Qwen3.5 397B

Pick GPT-5.4 if you want the stronger benchmark profile. Qwen3.5 397B only becomes the better choice if coding is the priority or you want the cheaper token bill.

GPT-5.4 is clearly ahead on the provisional aggregate, 93 to 66. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.

GPT-5.4's sharpest advantage is in knowledge, where it averages 92.8 against 65.2. The single biggest benchmark swing on the page is Terminal-Bench 2.0, 75.1% to 52.5%. Qwen3.5 397B does hit back in coding, so the answer changes if that is the part of the workload you care about most.

GPT-5.4 is also the more expensive model on tokens at $2.50 input / $15.00 output per 1M tokens, versus $0.00 input / $0.00 output per 1M tokens for Qwen3.5 397B. That is roughly Infinityx on output cost alone. GPT-5.4 is the reasoning model in the pair, while Qwen3.5 397B 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. GPT-5.4 gives you the larger context window at 1.05M, compared with 128K for Qwen3.5 397B.