In short, you want a NAS that isn't Windows based.
I don't think lordsmurf's reasoning was for Windows, but rather approach.
0. Most importantly, if a Raid-1 fails, you can connect it and read it like any other drive, you don't have to worry (if you encrypt, there could be variables). Look up "mdadm".
2. You're going to use more than 2 drives. Maybe not today, but you will. I started with 2, now I have 8 connected to my NAS (I'm in a corner now for connectivity that isn't USB). Also, USB connectivity is now starting to become questionable. You want Type B or Type A, but you DO NOT want Micro B. That being said, Micro B has just started failing me at times after years of usage (I believe the power to the controller is failing and not Micro B just can't deliver the amps).
3. ECC memory. There's a debate on this that I will not dive into. However, and I'm going to capitalize this, AMD'S LATEST CPUS SUPPORT ECC EVEN FOR DESKTOP COMPUTERS. This is amazingly being overlooked by home NAS users, although it's
4. Power consumption is completely up to you. Don't look at it like prefab NAS vs. PC, look at it by the total sum of it's components.
5. You don't directly write to a NAS in anyway (although I violate this, I'll explain later). So, don't edit video off your NAS or store temp documents to it or capture video directly to it.
6. It's not JBOD vs. RAID, it's application vs resource. In an enterprise application, the resouce will be an entire room or cage for 1 thing and 1 thing only. In your home, it will be a small box with a mix. A home NAS will have both a RAID and JBOD, not just 1 or the other. JBOD your disposable videos, RAID your non-disposable.
7. Ventilation is a concernf for the enviroment, but not that big of one. Those fans in those links are nice, but you could probably just cut a whole out and achieve the same effect. The fans inside of the computer are the most important.
8. Noise. Anyone can silence a box 2 feet anway from them, I mean dead silent and literally anyone.
9. Security is based off of user permissions with a typical *nix NAS. You can encrypt and all that, nothing changes here. Howver, you'll probably want a permission group for media viewing, and explicit user privs. for other things. *nix or windows, this should be transparent to the client.
I'd use FreeNAS or Open Media Vault (OMV) in a "Shuttle" like case with as many drive bays possible for it's size and a lower powered CPU. You have options...
an old Xeon mobo, cpu, ECC memory combo.
- Use a new AMD CPU with ECC memory. The Ryzen 5 2400GE isn't for sale yet (besides 1 ebay
dealer double charging), but the TDP of that CPU is 35W. With that CPU you can run ECC memory and the TDP, well, let's just say without lights on your computer, you won't know it's powered on under and NAS load.
- Some overkill i7/i5 monster off Ebay or what not. With that you won't have silence or good power consumption, but you'll have a system you probably already know, which can make up for some things.
In the end, working from a small computer case (microATX or smaller) is cheaper and superior to a Synology this or that, just not as easy to setup. However, setting up a NAS isn't hard, just maybe "foreign" at first (but actually VERY simple).
BTW, I strictly do silent SFF/micro everything in my house...everything. I won't even go over 2U blades, in fact I'm trying to turn a 2U into a 1U out of shame :-)
Example 1 BAD: For my photographs, I have a NAS in a 8"x10" case. I directly edit off of it using Lightroom for resource reasons. You shouldn't typically do that type of thing as I said, a NAS isn't really designed for high write operations. So this isn't a NAS per-say, but it is a headless machine running a 16TB RAID-1. (Reasoning is if lightroom curropts a catalog locally a certain thing happens, but off a NAS it doesn't. Why? No idea, but Windows' MKLINK works magic).
Example 2 GOOD: I have another NAS in a old, old, OLD shuttle case of the same dimensions. It's a headless machine storing "Scrap" media on it running something like 16TB as well, however I do not work off it. I personally simply upload and delete from it. The only other thing going on with it is that family members run clients that read from it for media (Audio/Vido). That is a media NAS, and I'm not violating any common beliefs of what a NAS is.
EDIT: I wouldn't choose Windows for a NAS because of licensing and foot print. In all honestly, I can't think of 1 positive to running Windows as an actual NAS. I'm sure there is one, but I don't see it right now.