If I was speccing a system for someone else, I would keep it simple. Tower chassis with about 8 drive bays and be done.
My "new" server is a 6yo NUC (tiny thing) and a couple 4tb usb hard drives.
On the upside it can all run off a small inverter, old battery, and solar panel. We lose power pretty often.
Never thought much about transcoding stuff. We don't bother with anything above dvd level. Can't see any difference, don't have anything to display it on.