Which do you use?
and why?

Thanks in advance.

I used to use LESS but moved to SASS + Compass because of how much more powerful they are, personally speaking SASS offers a much better pre-processor base compared to LESS which I see as a next level layer for CSS unlike SASS which is pretty much a new language in itself. When you combine SASS with Compass the your code becomes less cluttered, you are able to abstract a lot of the brains of the code into functions, mixin’s etc., and maintain a clean and consistent code base which LESS really doesn’t offer.

This is an interesting talk about Sass: http://shoptalkshow.com/episodes/056-with-ben-frain/

Okay thanks, I will skip LESS and proceed to SASS this will save me time I guess.

Man neither for me thanks. I happy with css. Why does it need changing?

These tools don’t change CSS, but just offer a different way of creating it. All the same, though, I’m like you, and don’t want to have to learn an extra layer of tools … though on larger production sites I can understand the attraction of something like SASS.