Depends what you're looking to use them for.. Highway I'd say Michelin LTX M/S2, granted their $169 - $200 a piece, Bridgestone Dueler and Handkook DynaPro are also great tires.
I have the Michelin LTX M/S (front) and LTX M/S2 (rear) on my X, they wear out pretty evenly, have great traction...