I prefer presta for the snob appeal. eeewww you bike has those fat stems?! that common chuck doesn't work on my bike, I only use an exclusive air pump.
other than a smaller diameter that fits better in narrow rims is there an advantage to presta valves?
With the presta, you don't have to worry about losing pressure as you remove the pump. It makes it so much easier to be precise in your pressure settings. To be honest, I'd use prestas on everything if I could get 'em...