Gorgon90
Harmonic Dive Bomber
My favourite 1 x 12" is the Trace Elliot Super Tramp Tube of which I have two. However as a hybrid amp I doubt most people here would be interested. Also as they are fairly large as 1 x 12" combos go, it probably wouldn't fit the small footprint requirement. Here's a pic of one on top of Marshall 4x12" (AVT?) to illustrate the footprint size.