I’ve been an avid Coda user for years but until Coda2 drops I’m using Espresso2 as my primary code editing environment.
It’s not perfect (no inline HTML validation, no built in Sass support, although some free ‘Sugars’ on Github add support) but as it’s a quantum leap from Expresso v1 thanks to the integration of MacRabbits CSSEdit application: in Espresso v2, Espresso and CSSEdit are now one!
It also has GUI support for lots of CSS3 features such as gradients and multiple backgrounds (for those that don’t like hand-writing CSS code – it even adds common vendor prefixes) and full support of HTML5 tags (section, article etc). It’s $79 so won’t break the bank (and it’s heavily discounted if you have v1).
Will it still reign supreme once Coda2 drops? Perhaps not, but until then, I’m loving using it on a daily basis and I’d recommend OSX code editors check it out.