Like SadieKate, I recommend the Steelhead. They are bomb-proof, and I've been using them for at least 5 years. They only bummer about them is that they aren't cross-compatible with Thule, but that shouldn't be a concern if you are never going to move them to a Thule-equipped car (or let your buddies borrow 'em).

I also use a King Cobra because as someone already mentioned, you don't have to throw the muddy front wheel into your car. However, I don't think it's as stable as a fork mount, plus it's so high up on the car.