A dream rig for me would be the most powerful computer that one can build occupying the least amount of space as possible. Any yahoo can build a specd out full tower PC, but making a small build that mops the floor with 99% of PC's out there is the real challenge.
So an ITX with rig with 295x2 or a small mATX with dual Titan X's/390x/GTX980s.
Silverstone sg 10 is a cool mATX case I'd consider.