I'm a big textmate advocate, but it's always hard to explain exactly why I think it's the best editor. It's really something you have to spend some time with (like OS X!). At the same time, textmate seems very basic if you have no experience with it. I remember when I first downloaded and ran it, it didn't seem like anything special so I trashed it and continued with BBEdit. Then I came across a video demo of what was possible and I gave it another chance. The best way is definitely by example so check out this screencast:
http://macromates.com/blog/archives/2006/04/28/html-screencast-inserting-tags/
If this doesn't win you over, I'm not sure what will.
http://macromates.com/blog/archives/2006/04/28/html-screencast-inserting-tags/
If this doesn't win you over, I'm not sure what will.