I bought some alloy wheels from the local recyclers recently and they came with presta valves. There are 2 reasons that I know of why they might be preferred - one, they can hold more pressure, secondly they use a smaller sized valve hole that would suit a narrower rim. Once I've sold the bike I've put these on I'll have zero presta valves in my stable. Not because I don't like them, they just haven't been in the wheels I've usually come across. I do have a few sets of woods/dunlop valves in 642, 635 and 630 sizes. I only found out a couple of days ago the following piece of trivia: the tiny little rubber tube you used to/sometimes still do get in a patch kit, is a replacement valve tube for a woods/dunlop inner tube . Which means I'm kinda glad I didn't throw away the inner tubes I have with these valves, but I don't think I have any replacement tiny little rubber tubes coz I didn't know what they were for and have probably thrown them away. End of story.