Aquariums that can be placed in walls and resized would be fabulous. And free-standing aquariums and the ability to change the finish color. And also:

-Ability to change gravel/sand color

-Ability to change background

-Ability to choose led lighting color overhead

-Choose either plant scape (lush plants everywhere) or hardscape (rocks and branches) or saltwater coral scape (corals and anenomes).

-And then choice of fish school to add to it (tetras and barbs/fancy goldfish/rainbow fish/assorted saltwater fish)