With features and prices: Here!
After trying TextMate, Komodo Edit, RubyMine & gEdit, I finally decided to use Netbeans. It seems like the only free IDE with full blown debugging support & method completion. Only downside: no (bug-free) git support yet.
BTW, TextMate feels great, almost sexy & is definitely a cool text editor - but the code completion is way to rudimentary for my taste and there’s no debugging support. I wouldn’t call it an IDE. RubyMine feels like… let’s keep this suitable for work & don’t say it out loud. Cool features, but I can’t see one single point for not preferring the free Netbeans IDE instead.