Using Anthropic Claude models for coding:
Opus is strong on analysis. Industry benchmarks show it’s strong at coding, but I find it ambitious and rangy. It drifts beyond its mission when struggling, and will charge down supposition paths without grounding.
Sonnet is good at tasking out work and quite good at following through on well-defined tasks, but can be short-sighted in terms of pattern and method reuse.
The current version of Haiku falls short. It shows its age with anti-patterns like aggressively duplicating code and hardcoding values, particularly when spins on a task.
So, for now, I live in Sonnet. I use Opus mostly for analysis on big problems. I’ve stopped trying to use Haiku for now. Would love to hear from someone who is getting decent results in complex code with one of the smaller models.