ok, i looked it up on all-glass.com...the standard 55g is 48x13x20. so it's not a 12" tank.
UNLESS the tank you're looking at really is 48x12x18, then it's less than 55g. i'm sure someone could crunch those numbers, but i just woke up! if that's the case, go with the 65g. my only deterrent is the height.
If I were buying a tank strictly for looks, I would always choose anything wider than 12"-13". My personal favorite is the 65, but 75's and 90's are absolutely breathktaking when fully planted and stocked with schools of fish.