I've been using MavensMate exclusively (ok, minus the odd developer console usage) for the development of all our products at S. P. Keasey and Proximity Insight and I can't recommend it highly enough; if you listen to Code Coverage it's obvious how much the community loves it too.
Resource Bundles FTW
Personally I find many aspects of MavensMate to offer productivity bonuses, the most obvious one being that your UI doesn't get locked out while saving code to the
Joe Ferraro (aka. Mr. MavensMate and the Saviour of Developers everywhere) provided an excellent YouTube video of how they work so I'm not going to explain them here again, I just wanted to draw attention to them for anybody who may have missed them as I did.