+1 for Textastic, which is my fave as well. But Gusto deserves a mention as the other top code editor for iPad.
You can't go too far wrong either way. I ultimately preferred Textastic because it is less web-oriented and more of a general programmer's editor. It supports more languages out of the box, allows custom roll-your-own syntax highlighting definitions, and has a really usable cursor navigation scheme.
But meanwhile, Gusto has one big killer feature for the web developers: a built-in browser for remote previewing/testing after you upload your code to the server. Textastic can do local preview of HTML and Markdown, but that's really no substitute for seeing your work in place on the server. Granted, you can multitask on over to Safari from Textastic, but Gusto just makes round-tripping your web code that wee bit easier.
Long story short...if you're mostly a web dev (which I'm not), Gusto deserves a look.