Pretty much all I want is an editor that loads quickly, shows whitespace, highlights matching parens, and does regex search-and-replace and find-in-files. Usually my choice has been EditPlus, but Notepad++ is a great open-source alternative, and gedit's another good one (although I think I've had to use grep separately with gedit).

I turn to jEdit for editing Unicode documents, NetBeans for editing C/C++, and DrRacket for editing big Racket projects, but those are extremely rare situations for me. Most of the time I avoid all three of them because of how long they take to load; I can almost always get in and out faster with plain Notepad.