Originally Posted by happypills

Off the top of my head;
there are way more rims that support presta (especially the high end like mavic)....
presta valves allow for easier and more accurate modification (the lowering of mostly) of air pressure in tires "on the go"
presta valves hold air better as you hand screw the top tight?
~the need for an adapter for a presta valve can be avoided with a pump that has built in support for presta valve