I know there are lots of fans of Coda and TextMate. I tried both, but neither was a good fit for me. While both are great code/text editors, they struck me as more general purpose editors and lacked specific web features, at least out of the box.
I think a lot of the decision comes down to the type of coder you are. I'm a recent convert to the Mac, and still use Windows at work. I actually really like Dreamweaver, even though I never touch its WYSIWYG features. But, I only like it when my employer pays for it
After trying Coda, TextMate, Espresso, NetBeans and Aptana, I finally settled on
BBEdit. If your primary focus is on web, I think this may be the best bet. And, at only $50 for the latest version, it is priced right, too. It reminds me a lot of the old Allaire HomeSite HTML editor that I used for years, but updated with a ton of modern features.
The good news is that all of these programs have trial versions so you can test them out to find the one that best suites your specific needs.