Wide is better...BUT harder to fit in the standard doors on the account of the bigger stand. The point is mute of course if you are going to build it in situ.
Any visual appeal of a tall tank goes right out the window as soon as I have to actually do something in the tank... Catch a fish, pick up something I dropped, rearrange aquascape...
Wide is always the best choice above taller tanks..............Wider, the species have a greater turning area to turnabout.......As for a taller, it is a tank that is set to be filled to the top with ornaments.....Tall tanks are great for aquascaping saltwater coral scenes..............