I've got American Star +2's on mine and they seem to be pretty good and priced reasonable. The only problem I have had with them is the powdercoating started peeling off after it got chipped up and power washed a few times.
On other bikes I have had laeger and roll design,I know have Walsh on my dale and they are far better than anything I've had.I don't know if they are the best ,but so far to me they are.
I checked Arens' website and he has Cannondale arms listed in standard and long travel. Says they were suppose to be available in the spring of this year.
I've been trying to call him, but all I get is an answering machine. Guess I'll have to email him instead. Has everyone that has American Star A-arms had good luck with them?? I will probably go with a +2 arm. I would like to go +3, but I don't know if that's possible w/o a long travel shock. I like to hit the trails occasionally.