How much space will you have available?
The Marineland/Perfecto 90g RR cube tank is a sweet tank, but requires 30" square.
A standard 90g RR is 48"x18" and is your basic rectangle.
If you wanted to go a little bit larger you can upsize to a 120g that is 48"x24" and is a real nice footprint to allow more aquascaping capability.
Upgrade to a 120, or any tank that has a 24" width or more. It makes a world of difference in you aquascape options as Russ mentioned. My tanks are all 18" wide and I have grown to hate them, lol.
If space is not limited, check out the Marineland Deep Dimension tanks. They come in varying lengths, but all are 36" wide.