As gchpaco points out, both sam and acme are pretty usable. Acme makes a good enough programming editor that I use it for all my coding at work, while I keep a tarball of the original sam port on a server for those times when I have to use a system with a crappy version of vi and no admin privileges to install something better.

Oh, and you can run Vim on Plan 9 now. But it's kind of like visiting a foreign country and eating only McDonalds.