I guess the first question is what do you want out of a tire/what kind of riding do you do?

For me, the Conti GP4000 has been really good. I really enjoyed the Open Corsas I had on for a while, but they just aren't very durable. Right now I'm running Michelin Pro Optimums - but you don't want to hear about those! They run larger than the Contis and the Vittorias, and so far have been quite durable. For the riding I'm doing (centuries up to an occasional double century) these tires are working really well.

JB