That's pretty tough as everyone has there own sense of style....In mATX I would try to find one that has a front bottom 120mm intake fan (80mm in a pinch). That way you will have airflow to the card intakes. Top blow hole designs are also preferable as heat rises. I find tool less designs to be overrated alot of the time but unless your getting the 25 dollar brown light special case it will work fine.

My preference is for Antec, Cooler Master or Thermaltake cases as they seem to be the best cooled, quality and functional design for the money. I have built some budget (very tight budget) machines using cheap cases and I really do not recommend going cheap. Fighting with dumb designs and feeling the paper thin metal flex is not very fun.

I have also worked with a couple of the more expensive ones (i.e. Lian Li) and while very high quality and very nice I could just never justify the added cost over a mid-grade case that is almost as good.

That is my $0.02 on cases...
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Core I7 4790K @ 4.7 Ghz
Corsair H115i AiO 280mm Water Cooler
EVGA GTX 1080 TI

Yeah I am having a bitch of a time finding a quality mATX cube that I would feel safe doing SLI in lol.....Apevia and Lian Li seem to be my only decent cube options at this point.
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K-SWISS Power cologne. Who knew you could bottle the scent of boner?