I have a 29g biocube and am very satisfied with it. For now its a FOWLR
but the stock lights can support most corals, maybe not SPS
and other high light loving ones but most of what you'd want you can have. No anenomes though, don't think the light is strong enough for them.
I have a set of nemos right now in the cube with a citron goby, dragonet and a yellow watchman.
Some great starter corals would be zooa's, leathers, mushrooms and candycanes.
Hope that helps a bit.
I also looked at the nano cubes but for the price I went with the Biocube.