Well the answer to this Totally depends on what kind of terrain you plain to ride on, your preferences for puncture protection, etc. My first thought is there's no question you should go to planetx.co.uk and get some Vittoria Hypers. I'm jealous. That's the only place I know of to still reliably get them, and it's ~$20 shipping to the US. Otherwise the Schwalbe Supreme would be my pick, I think. It's also a nice smooth tread for efficient road riding, but I assume being a Schwalbe, it'll have more puncture protection. They tend to make tough tires, though a little heavier and slower than some others.