In my experience, there is a very specific use case of one-shotting complex, long tasks with relatively vague or incomplete descriptions where Opus does substantially better than all other models I've tried, including GPT 5.5, GLM 5.1 and DS4. It seems to be better at inferring unstated requirements and creating a complete, working, reasonably well-designed solution.

However, that's probably not how most professional developers use LLMs. I tend to give well-specified, more constrained tasks, and for those, I find that Opus performs worse than other models precisely because it tends to infer unstated requirements and do things I didn't want it to do. In this situation, GPT 5.5 works better for me because it only and precisely does what I ask it to.