I had an NZXT H500i and the airflow was terrible, I switched to the Fractal Design Meshify C and have never seen better thermals it's absolutely wonderful. I have also built in both the Coolermaster H500m and the Corsair Obsidian 500D. My top 3 cases are the Fractal Design Meshify C, Fractal Design Meshify S2, and the CoolerMaster H500P. The Corsair Obsidian is a beautiful case but like the NZXT H series line of cases it is very restricted it looks like it isn't but it is, only has a few slits in between the tempered glass and the frame to supply air to the front fans. The H500M however like it's H500p counterpart has a mostly mesh front panel for air intake and two large intake fans. Personally if you're looking for a high airflow case, anything with a mesh front panel and top mounting rad support is the way to go as mounting the Radiator in the front for intake will greatly restrict thermals. My new check list for cases is a Mesh front panel, two to three intake fans, 240mm+ top rad support and of course a nice tempered glass side panel.