The Kel-Tecs are pretty nice, but have coarse sights and don't readily accept upper rails. I wanted one for a while but decided if I'd rather just get better with my pistol (which I did) than hope I'd have the chance to bust the folded Sub2000 out of hiding if I ever needed it. In any case, good luck finding one
About the best one around is the CX4 Storm, though. Very well-built, good capacity with aftermarket mags, and is built on the compact pistol-frame design rather than the "mag forward of the fire controls" design. But, it is also among the most expensive.
The best compromise really is probably the Hi-Point, though.