low noise

[TribalHound]

The lowest noise would come from using NAS grade SSDs, like the WD Reds below (plus you'd get much better speeds of read / write for Plex).

WD Reds come in 500GB upto 4 TB and are designed for 24/7 operation.
https://www.westerndigital.com/en-gb/pro...DS100T1R0A

Something like the Synology DS720+ or QNAP TS-253D has the capability to add NVMe for faster system or SSD caching and would support your file shares as well, just watch the heat generation and add more cooling.

If you need more storage (or a lower budget) be mindful if you switch to regular HDDs that the higher the capacity, the louder they get (now over 20TB), so you might want to consider the 4 bay versions with more SSDs, smaller HDDs, or a combination of both.

My main NAS runs 50% SSD & 50% HDD 4TB drives and is reasonably quiet, but I split them into two storage pools an SSD Raid and HDD Raid so that each raid contains the same disc types & capacities.

Hope this helps.