Just because it's a bit different to what you asked, and no one else has said it, I've found great results with the Terramaster D5-300 and D4-300. Make sure you get the USB 3.1 type Cs, but I've been fine with the plain rather than ones loaded with RAID.

For every USB 3.1 socket on the back I get 5 drives, I can increase capacity incrementally, and for spinning rust they are faster than they could transfer anyway.

I've replaced my machine with a Dell USFF box now and it all works great.

Completely understand if it's not your thing but you can add a drive box to your existing system without replacing anything. I'm currently up to 16 drives.

There something wierd going on with her eyes...