Iwata HP-C!
The HP-C has a .30mm fluid tip which is much finer (which in my opinion, is better), and atomizes the paint much finer for highlights, or shading.
The second choice would be a HP-BCS (gravity fed model). It has the .35mm fluid tip, which is a little cheaper to replace the needle and fluid tip, but it does not break up the paint as fine. But it can handle thicker viscosity paint. So it's a little more versatile, but not by much.
I believe that the HP-C plus has the teflon needle bearing, but I was thinking they put the teflon seal in the regular HP-C? I can't remember now! I would stay away from the models with the air adjustment valve under the nozzle. It costs more, and all you need to do is adjust your air regulator on the hose for the same effect.