Everybody has different ideas on what they want for a case.
The things I look for are:
Easy wiring, cable management can make a big difference on how it all looks when your done
Bottom mount for the power supply
Easy access for fan filters, they can get dirty quickly in some environments
Fans....at least one in front, one in the back and or sides. Fans for the top and bottom would make for much better cooling too, at least 120mm . 80mm fans will be waaayy too noisy
A 3.5" opening in the front is nice so you can install a card reader
Plenty of depth for those skyscraper heatsinks (7.5" or more)
Plenty of length for those long video cards (about 12" free space)
I do like my cases painted on the inside...but that's just a personal preference
I do have a HAF 912 case for my main pc, I bought the optional 200mm fan for the top