The absolute best one is made by Oasis Off-Road.
http://www.oasisoffroad.com/trailheadAirCompressor.html
But it's expensive, isn't portable and has to be hard mounted.
In a close second is the
Extremeaire, which I just ordered (portable version) through Mike at XtremeOff-Road. He just became an authorized dealer, so drop him a line.
In third place would probably be the QuickAIR compressors by Sun Performance... but you probably won't be happy with their duty cycle. (40 minutes @ 40 psi)