how does GLM-5.2 fare against fable/opus 4.8? I am thinking about moving my 5x subscription either towards the GPT equivalent or the GLM one (I heard GLM gives you 20x the token usage for the same price of anthropics 5x)
I find it difficult to compare LLMs in general. It will do better in some cases, worse in others. As far as I see it, most of it is marketing. You can try it out extremely cheaply though through their API and OpenCode. I personally would recommend it.
GLM is Sonnet 5 level, maybe slightly below. Probably Opus 4.5 level if you want an Opus comparison.
It's a good model that gets things done but it's just not comparable to Opus and a very very far cry from Fable. It does poorly with long horizon or very complex agentic tasks, but it's great and even cheaper than Sonnet for quick sessions.