Currently using a Logitech Cordless mouse.
This Logitech has two buttons and a scroll wheel. Has worked well for me so far, though I think it drags with a little more friction (heavier because of batteries is possibly part of the cause of that).
I prefer 5 btns - but only if they work, which is what they stopped doing properly on my former Kensington Optical Mouse in a box. That optical mouse was fast and light, but I do not miss the cord (good riddance to mad mouseigliitis!) or the way its buttons gradually died out on me.