Kakoune[1] has been posted recently here on HN to great reception. As a C++ developer, I think it has a very high quality codebase, especially considering how non-trivial it is.
As a user, it's been my main text editor for over a year.
It also has a vibrant community, jump in on IRC if you have questions or ideas.
[1] https://github.com/mawww/kakoune