I'm looking at two cases which can fit four hdd's. I've narrowed it down to a silverstone ps12 and a Sharkoon m1000.
The ps12 is ideal because it's smaller and has all four drives in a cage behind the fan meaning they get good airflow through them. The four drives would be grouped in sets of two meaning two drives, one above the other with virtually no spacing between them and then a 1cm or so gap between them and the next set of two drives. I don't like the idea of them stacked up like this but at least there is the fan blowing air through them.
I like the Sharkoon better, it's build quality and materials are way better. It also has better value being the same price but coming with two fans, 140mm front and 120mm rear as well as two usb2.0 and two usb 3.0 at the front compared to the two 3.0's on the silverstone. I can always buy a 120mm rear fan and a 5.25 usb 3.0 bay for the sliverstone but it's nice to have all that already installed.
My only issue with this case, is that it allows for two drives vertically stored, one on top of the other, on the lower side of the case in front of the fan while the other two would have to be placed in the upper part exposed 3.5 bay and converted 5.25 bay right below the disk drive. Both these would be generating heat without any airflow from the front fan. I'm wondering if the rear exhaust would be sufficient to move air from the upper front part where the additional two drives are located.
My pc would be on 24/7 and I'm thinking the silverstone would be slightly better of the two in terms of cooling or airflow through the drives in the long run.