Claude 3.5 Sonnet vs GLM-5.1

Pick GLM-5.1 if you want the stronger benchmark profile. Claude 3.5 Sonnet only becomes the better choice if knowledge is the priority or you would rather avoid the extra latency and token burn of a reasoning model.

GLM-5.1 is clearly ahead on the provisional aggregate, 83 to 41. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.

GLM-5.1's sharpest advantage is in coding, where it averages 60.9 against 49. Claude 3.5 Sonnet does hit back in knowledge, so the answer changes if that is the part of the workload you care about most.

Claude 3.5 Sonnet is also the more expensive model on tokens at $3.00 input / $15.00 output per 1M tokens, versus $1.40 input / $4.40 output per 1M tokens for GLM-5.1. That is roughly 3.4x on output cost alone. GLM-5.1 is the reasoning model in the pair, while Claude 3.5 Sonnet 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. GLM-5.1 gives you the larger context window at 203K, compared with 200K for Claude 3.5 Sonnet.