That's a subject that every developer in every discipline has had to deal with.
I've used everything from VI (vim), Notepad, Frontpage, HTML-Kit (a long time favorite on windows), Dreamweaver, HotDog (loved it), Brackects, Nano, Bluefish and more...
But for the last few years, I've been using SUBLIME. It has absolutly everything I need and is extremely versatile, powerful.
Hope this helps folks!