I like long tanks. Not deep ones. But that is just me....or that I don't have enough money for lighting that can penitrate all that way to the bottom on a deep tank
Shallow tanks that are wide front to back. The larger footprint both distributes the weight of the tank more evenly, and allows for much greater aquascaping options . I love looking at bowfront tanks, but I'd hate to be the poor guy who has to clean the front glass