Is it efficient to use css frameworks? If so, which one is best? Or any comparison comments?
Really it depends on your individual skills, preferences, and work style - for some people, it's faster to just work from scratch rather than trying to conform to someone else's design methodology; for others having a basic framework in place speeds things up tremendously. You really just have to try it both ways and see which works out better for you.
The "best" question is rather subjective, I don't think there's a single answer for that.