while not a tower case, but a 4U server rackmount i would suggest looking at the Norco RPC-4020, a pretty awesome case offering nearly ideal specs to max unraid out (that's in number of hdd's).
i never tried it (we have them mounted in server cabinets where i work), but i am sure you can also just place them in a tower-like fashion.
now before you start yelling about the roughly $300 pricetag, consider the fact that you get 20 sata/ sas hot-swappable bays build in! plus another 2 3.5" fixed hdd cages (i would make that cache and parity). at about $90 for a 5in3 cage this baby paid alread for itself before you count in the case... a way to look at it.
one thing that s*cks a bit are the 7 80mm fans - they are kind of loud. if your "tower" is located in the basement/ another room no problem (they are actually not as bad as many other server case fans), if not - you want to replace them with sth more quiet.
otherwise, solid design (very solid, weighs in just under 50lbs empty LOL), lots of space and config options.
a true contender to all the tower options. just do the math! between $50-100 for the tower case, another $90+ per 5in3 cage....
L