Synology makes great 1-4 bay NAS. Lots of documentation, fairly easy setup and one click installs of applications. The consumer grade ones are fairly inexpensive and work just as well.
I use Kod instead of Plex i on my devices and have it just night the NAS in the app. I signed the Kodi db to be in the NAS so all my devices track what I've already watched and progress of currently watching. It works great.
Get a UPS to protect your data in case of power outage. One that you can hook USB to a PC/NAS so it can tell the PC to shut down properly. A very common feature.