Given what you've said, Signal is still what you want and is good for it.

There are two main issues people have with Signal:

First is that it requires a phone number to sign up. That makes some people who want it to be truly anonymous unhappy. It's not meant to be anonymous, though. It's meant to be private. Those aren't the same thing.

Second is that it runs on AWS. This isn't a problem in the sense that it's possible for it to still retain privacy while running on AWS. Some people don't like it because they view the dependence on the infrastructure of an American company to be a risk to availability. They also believe that it would exacerbate a security flaw if one were found.

Personally, I know these risks and still find it to be the best balance between privacy, security, and ease of use.