Red Coral is my favorite: not just for reasons of stock and knowledge alone, however.
Red Coral has quite a large space, and it is laid out very nicely. I find Gold's and Oceans to be very tight inside. I'm a bit claustrophobic.
Red Coral is the most "kid safe" of the bunch of them, too.
There are no low and open tanks sitting on the floor that kids can reach into, and all of the plumbing is concealed. Of course, bringing my little guy in there is still a bit worrisome. But, the really big safety concerns that I have about the other places aren't much of an issue at Red Coral: though a child could reach into Zues' tank (live rock tub) at Red Coral.