Keep in mind it's much easier for a SW beginner(or anyone) to maintain good and stable water conditions in a larger tank. Just daily evaporation in a nano causes pretty large swings in salinity.
Possibly the nano cube 28 gallon. It has 150 watt hqi lighting, so your choice of corals are of a much larger selection than other nanos. It also comes with a wave maker and dual pumps. To me, it looks like a great nano. I own a 12 gallon and it has never let me down(3 years now!).