I have tried many others for many other things (via OpenRouter) but I have never compared LLMs on the exact same task; it's confusing enough with one engine... ;-)

Sonnet 3.5 for coding is fine but makes "basic" mistakes all the time. Using LLMs is at times like dealing with a senior expert suffering from dementia: it has arcane knowledge of a lot of things but suddenly misses the obvious that would not escape an intern. It's weird, really.