I think the 75G is going to give you the same amount of usable aquascaping space. Now if larger fish that need open space is a big priority, the extra 3" really adds a lot. Like rmalone, I like the not so tall look, but that is totally subjective. The jump from 12" to 18" front to back depth will really add tons of opportunities - and you can create plateaus in your reef rock to raise up those corals needing more PAR (if you decide on the 90).