I have a Steeda double hook quadrant. I THINK it just refers to the number of hooks it has that you can attach the end of the clutch cable to. It's just for more adjustability I guess.
Honestly, they are all about the same. No real need for one unless you've broken / badly worn the OEM one or upgraded to a heavier clutch.
I know several that are using the UPR quad. UPR brand stuff gets kicked around by many, but they really make some quality stuff at affordable prices. I wouldn't hesitate to buy their stuff.