Light.
Silent.
Room for long gfx cards.
Big steel case is always so heavy that aluminium is only practical material... thin enough steel case to be light would be very resonance prone.
Soft HDD mounting is already required by steel case and with combination damping mat aluminium case is acoustically better with still notably less weight than plain unlined steel case.
Also door is required for good component sound muffling cabability.
Hard HDD mounting... and dual chamber design makes:
- Free space divided to smaller areas further complicating wiring.
- Use of airflow inefficient, two 12cm fans just for few HDDs! (+noise leaking)
- Airflow of motherboard chamber is anything else than laminar.
And anykind window is always serious challenge to EMC. (which requires opaqueness to micro/radio waves)
No soft HDD mounting. Really complex design puts different parts to more cramped areas. Too little external bays pointing to extremely impractical direction. (and then some complain about doors!)
I'll add another vote for the Silverstone Fortress.
As for drive bays, I need at least 5 x 3.5" bays
So not enough of them, with dense spacing of that case four HDDs is sensible number for not blocking also airflow.
And if knuckles hit to anything when installing graphics card then case is plain cramped.