Bronze puffers/ A. Modestus are larger, and a 20+ Gallon tank would be needed. It is also reccomended that they be kept alone, but they might tolerate tankmates, it all depends on the puffer.
In your situation, I'd go for the Dwarf Puffers. They aren't that colorful, but they have great personalities, and they don't get big at all. They are also pure fresh, and they aren't that rare.
And you should check out the links that PufferPunk gave you. The Puffer Forum is a great source for all things puffer