Synology all the way.
I've used several different 5 and 6 bay units, personally and professionally. They've ALL been great. And, they ALL still work.

I am using a DS1512+ at home now. It's been in one of our branch offices, 24H, covered in dust, before we moved it to our main EU office, before we dismissed (which is when I brought it home).
10 years, 24H, tens of drives used over the years, and I just updated its OS last week. Still supported, still working, and I've even been using it as a DVR unit for my home video surveillance system.

Absolutely great products.