I wasn't too impressed by purrfect pets. Petco and petsmart have nice selections, but their fish are usually unhealthy and not properly cared for (I always find tanks with dead fish). Pet pantry warehouse is Ok I guess, I used to shop there quite often.
The place I love to shop at, although it is a little expensive, is Aquatic Wildlife in Manchester. It has an awesome selection of plants and fish, and you can special order anything you want off course.
House of Fins in Greenwich seems like a really nice shop. I'll have to check it out for sure! Another excellent shop there is Greenwich Aquaria. They have mostly saltwater tanks, but do have a large selection of FW plants. Not too many fish, but all in excellent condition.