When Avid set out to design the best disc brakes in the world, they knew that simple stopping power wasn't going to be enough. The best brake would also have to work in perfect harmony with your hand, give you perfectly precise control and be easier to install than a virus on your PC. Mission accomplished. Avid G2 Cleansweep Rotor features a standard 6 bolt pattern.
For the price, these rotors are quiet and stiff--a little bit fadey, but that's a $40 rotor for you.
I've been running Avid G2 160mm rotors for about four years with no problems whatsoever. As for the G3 rotors, I had to suffer with lots of squeeling and chatter, no mater how much tweaking I did. The G2's are a little heavier, but have more surface contact area, and are much more quiet, which is a reasonable trade-off. My opinion is to stay away from the G3's.
Albeit not fancy looking, they work great. I have not boiled a break with these rotors, and they have great stopping power. I have a 160MM in the rear and a 180MM in the front.