Problem is, to get a cube like Shuttle you have to go even
*smaller* than uATX!
Mini-ITX it's called.
I compared a very small uATX case, the
InWin L545, which is a very good case - to the Shuttle cubes.
The InWin was almost twice the footprint... if you're going to be carrying it around at all, you can't fit it into a laptop bag and it won't really fit under one arm, it's too long and too wide for that. If you just want to take up less desk space, it's grand! It's got a decent power supply and quiet fans and it's cheap, you can't go wrong. If you're only going to move it around once in a blue moon, again, it's good.
OTOH, if you plan on moving the thing around quite a bit, like once a week or so, you'll find the Shuttle and its equivalents like the Qbic, Icube, Gbox and others all a much handier size and shape. Some even have handles built right on top.