Mine are 10 gallon tanks. For a while there years back I kept adding new 10 gallon Qtanks as things got too interesting in the ones that were up-and-running. Can't do that forever in an apartment eh.
I'm a snob about plastic plants. (Besides, I hear they're very difficult maintenance.) My Qtanks have plants growing on bits of coconut shell, wood or small rocks ('plants on casters'). If it's time to medicate, they can all be removed.
A good idea in show tanks too, when you want to prune the scungy leaves out of the old Bolbitis you know...