I own both cases (well, sort of. I own the 800D)
Let's see:
Corsair: Great wire management. Looks great and clean. Heavy.
CoolerMaster: No wire management. Has removable motherboard tray. Lighter. Has two PSU mounts.
Both are airfiltered and have mounting for a 3x120 radiator on top. The ATCS has greater airflow overall, but is lighter. The Corsair is built like a tank.
I have an EATX motherboard in my Cooler Master. Inside, the wires are a kinda a mess, but I zip tied them the best I could. There are some cracks where dust makes it in since it has a negative pressure airflow. There's so much space, I'm pretty sure you could fit the longest video card in there and have a little space. The front filter is easy to pop out behind the front bezel, but the other bottom filter and PSU filter are more difficult. If you put in the bottom mid fan, you can't remove the PSU filter.
Inside my Corsair is my gaming rig, watercooled. It's heavy. Wire management was easy. The filter on my 800D was a very low-mesh wire screen. Doesn't catch too much. It's on the bottom and pulls out the back pretty far, so if you put it up against the wall, don't expect to clean your filter very much.
Which one do I like better? It's a tough call. I'd just say, go whichever you like the looks of better, and just think about what I listed.
Personally I like the Corsair 750W PSU (TX or HX), but what's the PSU with the Cooler Master? A CoolerMaster or Corsair PSU?