Any great open source terraform providers?

I’m looking for a provider that is really wonderful to use and makes full use of what terraform has to offer. Does anyone have an example of one like that? What kinds of things make for good providers and what makes them hard for end users?

AWS is my go-to reference, because aside from being a large one with well-known resources and access patterns, it’s first-party, maintained (with contributions accepted) by Hashicorp.

For example sometimes I think ‘I want to do x… You can do that to an S3 bucket’ (or between a VPC and a subnet, or whatever) - so I know where to look for an example.

It is old (in places) though, so it’s not necessarily an ideal resource in terms of using the framework (vs older SDK) everywhere, or tfplugindocs to generate documentation, etc. So I suppose it depends what you’re looking for.