Seagate Ironwolf is the WD Red counterpart, i.e. N.A.S. drives. These usually run slower and last longer.
I'd personally take the WD, I haven't had any issues with them so far
I shucked one of their WD Reds from the Easystore 8TB in a computer that I use for network storage and I'm quite happy with it, I want to get another for redundancy at some point down the line
There's nothing wrong with second hand / used parts, if anything, they're better since way cheaper
I wouldn't particularly feel comfortable spending $350 on a cpu that is outperformed on the newer top end cpu's like the 8700k for $20 cheaper, aside from which you have no room to upgrade in the future if you were to continue using the socket