Thats a question for the ages... here is the best answer..... there are several that have certain things that make them worth going to whether its customer service, great selection, what ever.. i do not have a "best but these are the front runners locally..... oh and in no particular order,,.

CB pets
Aquarium Designs
Aquatic Warehouse
Darby's Tropical

If i did not list one its because i don't go there for one reason or another!