For gpt, both OpenAI and Azure OpenAI, I think they are similar implementation, you just have to provide some additional parameters like deployment name and different URL.

For non gpt options, I like Claude and Amazon titan. Claude is definitely good.

I'm also currently learning to use llama.cpp I see it has a langchain integration and it's very fast with GPU. So it's useful to be but as a hobbyist.

I've got no experience with bard though. Is it any good?