I gotta chime in here with a qualification that as a poor boy raised in a agrarian economy, and only recently finding my personal net worth high enough to justify a performance automobile, I'm not yet had to purchase very low profile tires.
Out of the last three sets of Michelins I've bought I've had to have two of the removed from my car.
Both due to excessive vibration (first was an M&S rated touring tire) and the second (just recently), were $95 ea. tires for my minivan (Semetry). The last set were deamed defective and I replaced them with Pirelli P3000's -- no trouble in about 6000 mi so far. The Pirelli's were cheaper by a third, they ride smoother, and quieter. Of course I'm trying to keep it under 1g around the corners for the minivan.
Granted, these are not performance tires as such, but just a point to say that not everything Pirelli makes is crap and Michelin makes some stinkers as well -- this is really a tire by tire thing. Though I might buy a high performance Michelin, I'd never buy another set for any of my regular cars (IMHO the last good regular Michelin was the XZX -- didn't even need to be balanced practically). I've ran P300's and P3000's, and P400's (If I remember right -- I don't replace them that often) and have had no problems with them. I also had some Yoklohamas that stuck like glue but they last so short that it took some of the fun out of it!
I think I will try the Kumho's when It comes time if I can get them in the standard 951 sizes -- There have been some good posts on them. I'm thinking the Pirelli's and the Michelins are overated (esp. for the money).