When it comes to cooling, you should look for a case that supports good airflow. This is very important.
Good Airflow usually means:
1.) Front Intake Fan (80mm or 120mm)
2.) At least 1 Rear Exhaust Fan (120mm)
3.) Possibly a side panel intake or exhaust fan (80mm)
4.) Wire Management - Very important! This will ensure airlfow. Hide, zip tie, wire sleeve, etc... all wires that used in the centeral area in and around cooling devices.
5.) Room Temp - If you live in a desert with no AC. It doesn't matter what case you have... You will have very little cooling.
You want fresh cooler air to be drawn inside the case, which will mix with the ambient warmer air inside the case, cooling the ambient air and then the rear exhaust fan will remove the air.
For proper cooling of internal components like (CPU, GPU, HDD'S) you're ambient temp inside your case must be at least 10C cooler then you're components that you are trying to cool.
If your CPU is 40C you case temp should be no more then 30C.
This is primary due to the "HEAT DISSIPATION" cycle.
Continously mixing cooler air with warmer air...