I think my mid tower (CM Storm Enforcer ) is just right in its size. There's good airflow, and it's wide enough to allow for big aftermarket coolers, although it's not tall enough for SLI
Right and that is what I was gettin at. A mid tower is pretty good for most cases. But if you, and the OP intend to really upgrade the computer over time, you will probably be better off getting a full tower case.
As of now, my mid tower is not able to look the way I really want it too. It's not tall enough, and the depth is a bit short. I'll explain.
If I wanted to do SLI or Crossfire, I would not have room for 3 hard drives, because where the fan is on the graphics card gets in the way of the connectors of the hard drives. Therefore making me not able to put in the cable powering, or the SATA cable. It's just not going to happen. As of now, I am not able to have more than 2 hard drives because the bays, and my PSU cables are too close togeter, making the cable management look bad. (It's not that great in my computer, but I still have grerat air flow.
When you put this all together, it's really coming down to cable management. If you intent to have a high end computer, water cooling, custon tubing, giant raiderators, and CPU coolers. Of course you will want a Full Tower. That's only if you can see yourself there in the future. As for someone average, I think I should have gotten a better case for cable management.
OP that's something to look into, cable management. You want it to look nice right?