Smooth rim is the best in my opinion. My pads have lasted me ages, the brake works beast, my echo rim still has the sidewall colour for maximum sexiness. Echo pads, Echo rim, Echo frame, can't go wrong as the pads have been designed for those circumstances. I use tar of course (which is hard to see as my rim is black), but its brilliant because in say a drop gap or situation where you really want your brake to stick, you can slap tar all over the rim and it will hold brilliantly. And of course the oposite, if you want your brake to be a bit quiter and not to stick as much, just leave the tar alone for a while. The one downside to smooth rims which is not evident in grinds, and not so much discs, is the wet weather. But I don't like riding in the wet, so what am I losing anyway?