I have previously outgrown a Netgear RN102 (4TB total), and then a QNAP TS431P (12TB total) so decided this would be an epic build that will last a long time with possible upgrades along the way.
I was always going to be PC based for something of this size, so first decision was the case. After a fair bit if research I settled on this. 8 bays natively, but hot swap caddies for the 5.25 bays are inexpensive so I have 10 hot swappable 3.5in bays.
https://www.silverstonetek.com/product.php?pid=709&area=en
Motherboard is nothing too fancy, MSI B460M Mortar (6 Sata ports, but you lose 1 for the M.2 SSD)
10th Gen Intel i3 processor
16GB DDR4
120GB SSD to host the OS
500GB M.2 SSD to use for Docker apps
Extra SATA ports were added with this card to give a total of 11 SATA + 1 M.2
https://www.kogan.com/au/buy/d…ktop-computer-bg00024773/
I currently only have 6 of the 3.5 HDD bays populated with 4TB WD Reds, this meets current storage needs but gives plenty of room for expansion