If I had to choose only one, I'd choose presta. The only down side to them is that cars don't use them so much of the public infrastructure doesn't support them. But from a valve and tube reliability point of view, I prefer presta.

That said, on my son's old mountain bike with Schrader valves that my wife still likes to ride, I haven't put a grommet in - I just stick with Shrader valve tubes for that bike. Kinda like how I haven't replaced all the flathead screws I use with Phillips head even though I prefer those.