Server hardware recommendation

What server hardware/OS is recommended?
I’m right now testing version 2 on a HP Proliant with 2012r2 & deduplication. It works fine but Windows server feels a bit overkill.
If I go for a 4 drive rack NAS what brand/model is recommended? Any NAS with dedup?

There will have around 50 clients to be backedup.

I am not aware of any NAS that will run UrBackup now that the QNap platform has been mostly deprecated.

If Windows Server seems overkill (could you clarify this? Is the expense overkill?) perhaps you could use one of the Linux server distros? Do you need the HP server for other duties?

The HP server is bought for this (test),
Thought Qnap, Synology and Thecus should be a more slimed/dedicated solution, but I might have to reconsider that?