Speaking saltwater(because im not to sure about their freshwater selections, never look at that stuff)
CF (caribbean forest) has the best selection of inverts, RS (reef shoppe) has the best selection of high end corals and colonies, and ABC has the best frag selection. They all have your typical fish. Although CF has had a great selection lately of fish!
They all have their pros and cons. If you have time i would hit them all up. CF and RS are only about three mins apart so if your going to go to one of them id go to both. RS is closed only mondays and CF is closed only tuesdays so if your going to go, dont go either of them days so you can go to both!!
Id go wednesday because they will both be open and have gotten in recent shipments.
Good luck and enjoy whichever one you go to. You wont be disappointed!!