I might not be the best person to ask. I’m running 3 servers at home currently that are all desktop towers. With a 3->4 (3x5.25”->4x3.5” [0]) converter I can fit 12 drives in each tower. Across all 3 I have just over 150TB. There are some nice server chassis that can handle 20 but I’m more comfortable with tower hardware and when I hear “SAS backplate” my eyes glaze over...
I’m a big fan of UnRaid for my server OS but I know it’s not as advanced as some offerings on the market. I enjoy it’s ease of use and management of VM’s/containers.