Personally I like the dogface puffer, I've had one in a few of my tanks and they are a crack up. I've never met a porcupine that wasn't a nipper, especially in your size tank, that's likely why you will see many recommendations for larger tanks, I see them returned to the lfs all the time because of aggression. Any of the other puffers with the exception of the small Canthigaster puffers will get too large for your tank. I have my current yellow belly dogface with angels and even a lion with no problems, I;ve never had a problem with nipping or aggression with any of them.