Comparing Opus 4.8, GPT-5.6 Sol, and GLM-5.2
I've been a heavy Claude Code user since I dropped off Cursor back in January, and after half a year of running Opus on high effort as my daily driver, I finally sat down to see what the other two frontier options actually feel like: GPT-5.6 Sol inside Codex, and GLM-5.2 inside Cursor. This is a first pass, not a benchmark. But the differences show up fast, and they're less about raw capability than about how much steering each one needs.
Why I stuck with Claude Code
Claude Code with Opus has been reliable in a specific way: I know where the edges are. Tell it to do something and I generally know the outcome before it runs. That predictability is worth a lot, even through Anthropic's downtime and the occasional sense that a model's behavior shifted underneath me. Reliability beats novelty when the tool is load-bearing.
Curiosity won anyway. Both Sol and GLM-5.2 have a lot of hype around them, so both are getting a real trial on real work.
GLM-5.2 in Cursor
The initial, unscientific impression of GLM-5.2 is that it's good. Call it 75 to 80% as capable as Opus 4.8. It gets things done without much intervention and mostly stays on the rails, though it sometimes wanders down an implementation path that needs correcting.
Two confounders help it, and I want to be honest about them. One, Cursor is a good harness. Two, our team runs an extensive developer harness module: skills, documentation, helper scripts, a large pile of team-specific context that gives any model an edge. How GLM-5.2 would perform naked, hitting the API through a simpler agent, I genuinely don't know.
One habit across all of this: force thinking as high as the tool allows. Not max, usually the tier just under it, like high.
GPT-5.6 Sol in Codex
Sol on high thinking seems reasonable on capability. The problem so far is inertia.
Ask it to do something, or suggest something be done, and it says sure, it can do that. Say "okay, go do it," and it says yes, it can absolutely do that. Then I have to say, explicitly, no, go do the thing, now. It reads the letter of what you wrote and pays less attention to the intent behind it, so you have to give it more direct instructions than I'm used to giving.
That friction is hindering my evaluation more than any capability ceiling is. I'll keep pushing on it, because the pedantry might just be a prompting problem on my end.
Where I've landed for now
Big tasks and anything that needs writing, design docs, blog posts, stay in Claude with Opus. Small and medium tasks get delegated out to Cursor and GLM-5.2. Sol stays in the rotation as an experiment until I figure out whether the inertia is the model or me.