1) 2002+ RC51 - It's just a dead sexy bike, and the twin sound gives me a boner.
2) 2006 R6 - Delicious top end. I like the exhaust, especially since it doesn't look like the whale penis of a stock exhaust that came on the 03-05 models.
3)2004-Current R1- Another BEAutiful bike.
1. RC51's - agreed a dead sexy bike, but too heavy and uncomfortable to be used for anything other than a strict track bike. The seats get HOTHOTHOT, even moreso than a newer R1, and they just aren't comfortable.
2. 06 R6 - too small of a bike...feels like a Big Wheel when you're sitting on it.
3. 04-up R1 - best bike ever made, hands down...and that's mainly because I own one.