Like Jim said the Comp3 is pretty much strictly for competition, while the 1 & 2 are better for defense. I preffer the Comp 1 for pocket carry, but the comp2 gets the nod for carry in a speed loader pouch.
As for the Safariland being prefered over the HKS, I'd bet it goes pretty much 50/50. Each do some things better than the other. Safarilands can be had much smaller for pocket carry, but HKS has better retention of rounds when carried in something like a split-six belt carrier. HKS also makes a loader to fit about every revolver made with a swing out cylinder. I have trouble finding Comps for some guns.