Another vote for the sub that is reasonably sized for your large room.

I recognize you are dealing with neighbors but 'a sub too small' (the title of Negative Orange's new acoustic album) will be disappointing and you may find yourself trying to turn it up too high and getting a more rattle sounding experience instead of smooth bass and LFE. At first the rattle sounds impressive, then you realize it's not a natural sound and it becomes annoying.

With great power comes Awesome irresponsibility.