That is a tough one. There are so many morphs of either to make it even harder. I liked owning a cyano, because the little spots and they get bigger. They are supper aggressive and mine used to go after me doing water changes.
Rio Cazones are the nicest (looking)Carpintis strain/morph I've seen. They were available a few hours from me a while back and I'm still kicking myself I didn't try harder to find a ride. The carpintis I do have is one of the smallest fish in my 90 gallon and still isn't afraid of anything- he eats shrimp out of my hand and tries unsuccessfully to boss everyone in the tank around. I have a hard time taking pictures of any of my other fish because he's always crowding the shot. He's on a mission to open up the waterproof case on my GoPro as well.