I'm a little surprised by the sentiment here that LLMs don't do well with Elixir. I've had a pretty good experience using AI tools on Phoenix/Elixir side projects.

LLMs are definitely a lot better at Elixir than they used to be - the gap has closed somewhat. I still perceive a gap though, especially when trying to do more complicated things in Phoenix and LiveView (as opposed to just raw Elixir.)

Which LLMs do you use that you find are best with Elixir/Phoenix?

I've only used LLMs with Elixir, so I don't have any other experience for comparison, but I've found that although Claude frequently employs the wrong approaches in Elixir, I usually know when he'll have trouble and just ask him to read pertinent documentation first. So long as he's read the manual he seems to do just fine.