I can tell you what I've had, but they were on a Grand Prix w/ 16" wheels...
I've had Michellin Pilot XGT-Z4's, and Bridgestone Potenza RE-730's. Both are Z-rated tires, but the Potenza's don't have the M+S endorsement (mud and snow) meaning that they put down more rubber per square inch, but they would be useless in the winter. Both make great rain tires, and are excellent performance tires.
I had the Pilots first, and when I got the Potenzas, I initially didn't like them as much. The sidewalls of the Potenzas aren't as stiff, so they feel sloppier in transitions from hard left to hard right and vice versa. At first, their traction limit seemed no better than that of the Pilots, and I didn't hook up any better at the drag strip like everyone on the GP forum said I would.
That all changed after my first autocross on the Potenzas. These tires are amazing! Since I got them "scrubbed in" there, they're performing alot better. The next time I went to the track, my 60' times dropped, indicating that I was in fact getting better traction for launches. It may be in my head, but I swear they stick better in corners now, too. At $94 per tire in my size, I'm quite pleased. For comparison, I paid $124/ea. for the pilots, and Nittos are somewhere in the neighborhood of $160 each. Definitely check out tirerack.com.