As a general rule the longer fin base, and more sweep back, gives you more drive. Like the AM's (1 & 2 - bigger boys should take the bigger options). Kelly 3.0 is very similar.
Less rake and bigger tips, and less base, provides more maneuverability, and allow for tighter turns in the pocket...
Quad Set-up - Big Fins front and back definitely gives you more drive (but less maneuverability). For me, I like the drive down the line...
But by all means, play around with your fins. A mate of mine swears by using 4 side fins, 4 full sized side. For short boards he swears by AM's up front and GX side biters on the rear. He favours GX over the specialty Quad Fin GXQ (in FCS).
Futures - AM2 is the large one, and AM1 is smaller
FCS - G-AM is bigger than AM-2.
I've always found that stiffer fins give you more drive too, but the flex fins are probably better in small waves, and are also more forgiving.
If you love singles, just make sure the leading edge is nice and sharp (not blunt). A blunt leading edge will cavitate more easily when you crank into turns, and the cavitation means spin-out. I ride a quiver of singles (short boards) in amongst other stuff, and I'm yet to spin-out a single fin, but the fins are all sharp leading edges, and they are all True Ames Fins.
www.trueames.com/
