No help to the OP, but I have just bought 2x NAS boxes
For one I got 7x 2Tb Seagate Barracuda Green.
For the other I got 7x 3Tb Hitachi
So far after, about two weeks, I have had two of the Seagates fail. Lost all data in that NAS despite dual redundancy - It was still building the stripes when the failures happened. I made the mistake of putting data on there before I had finished the build process.
Neither drive failed Seatools diagnostics, so I have 2x 2Tb drives that I don't trust & can't return. Sigh.
When I mentioned it to my brother who has been in IT support longer than most of you have been alive, he just said "Seagate! What did you expect?"
The plan is, once I get it all working locally, to move one of the NAS boxes to a remote location. The local NAS will handle TimeMachine backups (Hourly backups for a day, Daily backups for a month, Weekly backups forever). Once a week, I will copy the local backups to the remote box. Via rsync so it won't take all week to do it.
part 2 any opinions as to which brand is best
With Hard Drives, it is not a question of if the drive will fail. Just when. Plan for it.
Unless mistreated, drives tend to fail early, as in my case above, or not for several years. Seagate do have a reputation for early failures, but all the companies have had their issues with quality control over the years.