I think it's worth the effort to learn emacs or vim. The point of these hard core editors is to keep your hands on the keyboard and not constantly switching to the mouse which many claim makes you more productive. Also, these editors work on many platforms.
If you don't want to learn the hard core editors, then I'd recommend Textpad, JEdit or Crimson Editor. JEdit is a editor that I believe is written completely in Java, so it runs on nearly any platform that can run Java.
Anytime, I see comments about editors I'm reminded of this quote from the Pragmatic Programmer -
"A surprising number of people we've met use the Windows notepad utility to edit their source code. This is like using a teaspoon as a shovel"