I carry a Smith & Wesson "Extreme Ops" folder (like the one pictured below, but in the black/gray camo pattern).
The main thing I look for in a knife is the pocket clip. I carry in my front-right pocket, and like having a reverse clip so it is in a position to be opened as soon as i grab it from my pocket. With the standard clips, I have to turn the knife around in my hand before I can open it.
This knife not only has the clip in the right position, but also is a well-balanced and sturdy knife. The main thing I dislike about it is that the pocket clip is held in by tiny screws that I don't have a proper screwdriver for. So every time it comes loose (which is often after carrying it every day for several years), I have to go borrow tools from my dad.
ETA: Wanted to add that opening this thing is a breeze. In the picture below you can see the blade has a sort of nub that sticks out from the front of the blade (near the handle). When closed, this nub protrudes from the spine of the handle. I find that pushing this nub opens the blade far enough that a light flick will open it the rest of the way. Since the nub is part of/attached to the blade, it makes this method of opening legal (i.e. not a switch blade). In fact, I never use the thumb stud to open my knife...