Well, after much research and analysis, I came to a decision.......
this is going to be just like every other computer purchase!!

I'll research this to death for a month, then wind up buying what I wanted to start with.

So far, I'm leaning toward a NAS for the storage and a separate Home Theater PC (HTPC) to be the server. It's just getting too difficult to justify $500 +/- $100 for a NAS that acts as a media server, web server, etc. The standalone NAS devices, including Synology, use 3-5 year old technology for the CPU, RAM and motherboards -- at least those for home and small businesses do. My current NASes have an Infrant Technologies branded SPARC CPU and an Intel ATOM. Both are running Linux modified for their hardware.
I think by building an HTPC server, I can leverage my existing hardware for storage and backups, reduce the load on each for non-storage tasks, and build the new HTPC with better specs than Synology offers at half the price.
I plan to upgrade the disks in my newer NAS, too. Need to replace the 4 x 2TB 5400RPM SATA II 3g/s drives with at least 4TB 7200 RPM SATA III 6g/s drives.
I also found out Seagate and WD have recently admitted they've been marketing SMR-based drives as NAS-specific items. SMR creates a write delay that can cause a timeout when a NAS attempts to rebuild a drive causing the rebuild to fail. From my reading, SMR disks are not suited for NAS use at all.
WD sent out a list of the SMR disks they offer at present, so NAS users can select CMR drives if desired. Seagate hasn't offered that info yet, but probably will have to.
The real issue isn't the SMR itself, but that the drives are not sold with the SMR design disclosed before -- or after -- purchase. Only when you can't get a NAS drive to finish rebuilding will you figure it out.
Intel seems to be the CPU for a good HTPC. They have the Quick Sync Video technology that helps encode video to H.264/H.265. AMD Ryzens can do the job, but they have to brute force the encoding at the normal CPU process level. More cores can help, but by the time you get a good enough core count, you've spent as much on a Ryzen as you could have spent for a comparable Intel CPU.
I have a workstation with a very good i7-7700K CPU that would work. So I also have the option of moving that over as a server and replace it with a new workstation. This PC is 3 years old as of March, but after specing out parts, my CPU, motherboard and 1080 NVidia graphics card could be sold for more now than I paid in 2017! I guess I bought the right stuff back then.

Not sure if you've seen XPENOLOGY, but I could use that to install Synology's DSM on my own hardware. There are several other free NAS software programs to choose from. FreeNAS seems promising. The ZFR file system appears to have advantages over BTRFS. ZFS was designed by Sun Microsystems, and FreeBSD is using it now. FreeNAS is based on FreeBSD (go figure!).