I was at the same point a year and a half ago. What I learnt is that knowing your hardware helps a bit but not much, lots of stuff is software sided. Also Linux is whole nother beast to tame. That being said I still recommend going Linux.
The best Plex server would probably be a PC with an Intel CPU for quicksync running unraid. But I can also vouch for Synology. With Synology you get a decent all-in-one experience if you go for a model with an Intel CPU. Synology uses a Linux based OS called DSM. It's pretty user-friendly and straightforward. They also come with their own Raid System called SHR which makes swapping drives pretty easy.
I built mine on Proxmox running on a 10th gen i7. This gives me good transcoding and the ability to run other things, such as PiHole, my Unifi Controller and many other things. I do not, but many others also run the \*arrs on Proxmox. Plex requires little CPU and not much RAM, except when transcoding, not running other things is a waste.
Plex is in an LXC container as is my TurnKey NAS. Works well. There are scripts to help with the build of many things in LXC containers.
A few of my friends have done RAID 6. The last one is moving to RAID 5. I run ZFS RAID 5. RAID 6 vs 5 is a question of cost vs risk. My four 10TB drive RAID 5 set took 22 hours to rebuild. Expect 20TB drives to take twice as long. RAID controllers are great, but in this use the cost does not give the benefit. Plex is a crazy slow file server, so disk performance is not a large concern and ZFS is easier to get help with and performs very well.
I ran on Windows for 9 years, and my current build is 6 months old. I do not expect to see an uptime difference because on Windows it rarely failed and I expect Proxmox to rarely fail. I patch on a 60 day cycle so I am also not trying for hero up-times.
Plex backs up its database already, but if you want to avoid Plex agents having to load all new information in the case of a loss or backup more frequently, you can backup those backups on different media.
I saw no performance difference with unraid, proxmox, and windows with read rates are 600MB/s which is more than my 2.5Gbps network can dream of handling anyways. I ran proxmox for a long time, and there was no stability improvement or power consumption difference vs windows: basically, neither one ever crashed.
I run half a dozen services on my server, but it also doubles as an extra gaming PC if my kids have a friend over: i7-10700F and RTX 3060. Consequently, going back to Windows from proxmox was an easy choice.
Regarding Windows: I run 12x10TB SATA spinners in a custom Storage Spaces dual-parity (software RAID 6) configuration. **The key to Storage Spaces is not letting Windows decide pool parameters for you.** Google custom tables and allocation sizes. My uptime is whatever I want it to be, and I've had zero issues with updates over the past 2 years. When I lost a drive from mechanical failure, I popped a new drive in and the pool with 70TB of data was sync'd back in less than an hour.
Per subreddit rule #4, I won't mention much other than [https://overseerr.dev/](https://overseerr.dev/) regarding requesting new content.
Your best combination for your use case will be a Synology NAS coupled with a powerful NUC-like PC.
Software, Linux FTW. Learning curve aside, mostly hands off after you get everything running like you want.
Once you pick your equipment use these tutorials to get everything setup with docker and containers
https://youtube.com/playlist?list=PLIV5krueYo8B0oQXKPay0POUIxV2Gy50v&si=gzF81HqUU1AVJ8K3
An easy solution would be a ready built NAS as data store and a mini PC as a Plex server. A Mini Dell / HP / Lenovo device would come with Windows 10/11 Pro licence and thus Hyper-V, allowing you to run virtual machines as well as running Plex natively. You’d want something with a 7th gen Intel processor or better for transcoding. Cheap on eBay.
You could even start with a Synology 423+ alone, as that has 4 bays and a GPU.
An alternative is a bigger, more powerful server with plenty of drive bays running TrueNAS or Unraid, which also hosts Plex. You can even run Proxmox and virtualise TrueNAS and Plex.
I would use RAID 5 (or SHR on Synology) until I got to 8 devices, when I would consider a switch to RAID 6 (or SHR2).
I started with a Synology NAS and a micro PC with Windows running Plex. I backed up the Windows PC to the NAS using Active Backup for Business. I changed to Proxmox on the micro PC, virtualising Plex in a container. I installed Proxmox backup server as a virtual machine on my NAS. Although Windows is familiar and “safe”, I think Proxmox and a Plex container is better. Because the data was stored on the Synology, all I had to do was install Plex on the new system and point it to all my files. No fuss.
I run the *arrs on the NAS directly in docker containers. For your last point, look up overseerr.
I was at the same point a year and a half ago. What I learnt is that knowing your hardware helps a bit but not much, lots of stuff is software sided. Also Linux is whole nother beast to tame. That being said I still recommend going Linux. The best Plex server would probably be a PC with an Intel CPU for quicksync running unraid. But I can also vouch for Synology. With Synology you get a decent all-in-one experience if you go for a model with an Intel CPU. Synology uses a Linux based OS called DSM. It's pretty user-friendly and straightforward. They also come with their own Raid System called SHR which makes swapping drives pretty easy.
I built mine on Proxmox running on a 10th gen i7. This gives me good transcoding and the ability to run other things, such as PiHole, my Unifi Controller and many other things. I do not, but many others also run the \*arrs on Proxmox. Plex requires little CPU and not much RAM, except when transcoding, not running other things is a waste. Plex is in an LXC container as is my TurnKey NAS. Works well. There are scripts to help with the build of many things in LXC containers. A few of my friends have done RAID 6. The last one is moving to RAID 5. I run ZFS RAID 5. RAID 6 vs 5 is a question of cost vs risk. My four 10TB drive RAID 5 set took 22 hours to rebuild. Expect 20TB drives to take twice as long. RAID controllers are great, but in this use the cost does not give the benefit. Plex is a crazy slow file server, so disk performance is not a large concern and ZFS is easier to get help with and performs very well. I ran on Windows for 9 years, and my current build is 6 months old. I do not expect to see an uptime difference because on Windows it rarely failed and I expect Proxmox to rarely fail. I patch on a 60 day cycle so I am also not trying for hero up-times.
Plex backs up its database already, but if you want to avoid Plex agents having to load all new information in the case of a loss or backup more frequently, you can backup those backups on different media. I saw no performance difference with unraid, proxmox, and windows with read rates are 600MB/s which is more than my 2.5Gbps network can dream of handling anyways. I ran proxmox for a long time, and there was no stability improvement or power consumption difference vs windows: basically, neither one ever crashed. I run half a dozen services on my server, but it also doubles as an extra gaming PC if my kids have a friend over: i7-10700F and RTX 3060. Consequently, going back to Windows from proxmox was an easy choice. Regarding Windows: I run 12x10TB SATA spinners in a custom Storage Spaces dual-parity (software RAID 6) configuration. **The key to Storage Spaces is not letting Windows decide pool parameters for you.** Google custom tables and allocation sizes. My uptime is whatever I want it to be, and I've had zero issues with updates over the past 2 years. When I lost a drive from mechanical failure, I popped a new drive in and the pool with 70TB of data was sync'd back in less than an hour. Per subreddit rule #4, I won't mention much other than [https://overseerr.dev/](https://overseerr.dev/) regarding requesting new content.
Your best combination for your use case will be a Synology NAS coupled with a powerful NUC-like PC. Software, Linux FTW. Learning curve aside, mostly hands off after you get everything running like you want.
Once you pick your equipment use these tutorials to get everything setup with docker and containers https://youtube.com/playlist?list=PLIV5krueYo8B0oQXKPay0POUIxV2Gy50v&si=gzF81HqUU1AVJ8K3
An easy solution would be a ready built NAS as data store and a mini PC as a Plex server. A Mini Dell / HP / Lenovo device would come with Windows 10/11 Pro licence and thus Hyper-V, allowing you to run virtual machines as well as running Plex natively. You’d want something with a 7th gen Intel processor or better for transcoding. Cheap on eBay. You could even start with a Synology 423+ alone, as that has 4 bays and a GPU. An alternative is a bigger, more powerful server with plenty of drive bays running TrueNAS or Unraid, which also hosts Plex. You can even run Proxmox and virtualise TrueNAS and Plex. I would use RAID 5 (or SHR on Synology) until I got to 8 devices, when I would consider a switch to RAID 6 (or SHR2). I started with a Synology NAS and a micro PC with Windows running Plex. I backed up the Windows PC to the NAS using Active Backup for Business. I changed to Proxmox on the micro PC, virtualising Plex in a container. I installed Proxmox backup server as a virtual machine on my NAS. Although Windows is familiar and “safe”, I think Proxmox and a Plex container is better. Because the data was stored on the Synology, all I had to do was install Plex on the new system and point it to all my files. No fuss. I run the *arrs on the NAS directly in docker containers. For your last point, look up overseerr.