Choosing seems even harder nowadays, what with SASS, LessCSS, CleverCSS, etc.
I've been using Compass, a set of SASS libraries that (among other things) re-implements Blueprint. I love Compass; I like SASS a bit less (especially where syntax is concerned.)
Luckily for you, Sass 3 will have a new CSS-like syntax. You can even use it right now if you want: http://github.com/nex3/haml/commits/scss. I believe it works great with the Compass 0.10 prerelease.
I've been using Compass, a set of SASS libraries that (among other things) re-implements Blueprint. I love Compass; I like SASS a bit less (especially where syntax is concerned.)
http://wiki.github.com/chriseppstein/compass/