Second Zepper's suggestion for the Microfly. It's AWESOMELY compact, and you can fit an awful lot of stuff into it (some reviews even say there's space for a watercooling unit for the enterprising types - just to the left of the drive bays where there's open space).
Two case fans, two 5.25" and three 3.5" bays are pretty impressive, along with the usual front panel ports, etc. I was eyeing the Q-Pack, but the 1" extension won me over.
I do like the CoolerMaster case, but it's a bit big for a MATX application.
BUT, it's a bear to cool this thing, since there's only a limited amount of "fannage" you can put in this thing. Make sure you get a GPU cooling solution that exhausts the back - it gets really warm inside the case with that little airspace.
Good luck.
PM