i have a few fish that i can pet.. my oldest angelfish, Gabriel will let me touch him most any time. A couple of my peacock bass, a cool one i just got a couple months ago that we call Buster, and my Dozer that i raised since he was 2 inches.
the RTC, but that pretty much goes without saying, most RTC will eventually learn to come up for food and will let whoever is giving them food pet them. Rocky, the bigger of my two oscars will be very friendly and almost let you touch him.. but not quite. and Houdini, the Marble/RTC hybrid, now that he's out of hiding, will come up to the top of the tank now and then, but isn't ready for contact yet.
and the P. Altum angelfish, they are a curious bunch, they come to the front of the tank when i'm looking at them and they come to my hand when i put it in the water. They must be incredibly easy to catch in the wild if they are that curious.