Pretty hard to beat a KX-2. Yes, I know it includes other modes, but what's the harm if you don't pay a weight penalty for it? The combination of small size, stellar performance, internal battery, integrated key and superior antenna tuner make it awfully attractive for portable ops. After all, you can leave the mic home!
Granted, a bit more expensive than some of the others on the list by N6MST (also some good rigs there), but very effective.