My current favorite is my Emerson CQC-7B. I've also got a Commander, a Benchmade 710 Axis and a Gerber Covert. I like them all but the CQC-7B seems to be the best combination. Small enough to fit neatly in the pocket, reasonably priced, extremely sharp, and very fast opening.
My favorite folder however is, by far my TOPS Magnum. However, it doesn't count for this topic it is much too big to carry in my pocket. I need the sheath.