You can use anything you want for a frag tank...even a 5 gallon bucket
It really depends on what you want to grow my man.
A nanocube would be fine, but why spend a lot on a cube, just get a 10 gallon tank and save a little and invest it in a nano skimmer and some powerheads and filtration devices...that's what I would do anyway if I were in your situation...Good luck