Unless you're obsessed with manually controlling every bit and piece, I definitely recommend Chirpy
(until further progress on JustCode and Thunder's been made). No more NuGet packages of dotLess or YUI compressor, no more pre/post build tasks - just edit your .less / .css file, hit save and you're done....
It comes with some basic syntax highlighting for .less files (so no more need for Mindscape Web Workbench - with their new annoying please upgrade pop-ups wohoo!)
So far the only downside of Chirpy is the inability to bundle, but that's going to be part of .NET 4.5 anyway...