I've always liked the ultrastar line. Used to be made by HGST and then WD bought them. I'm using specifically the HC530 14tb. The line has a long history of being very reliable enterprise drives.
I've bought mine from both goharddrive and serverpartsdeals. Both are reliable resellers of used storage. They'll warranty the drives for 2 or 5 years depending on which you to with. Prices are ~$130-$150.
Ps. One of the listings for the HC530 on goharddrive or serverpartdeals is incorrectly labels as HC520. Just pay close attention.
As far as raid goes, Raid 10 is currently very popular for its speed and drive failure tolerance. Remember, raid is not a replacement for the 3-2-1 backup rule. Raid has some fault tolerances for bad hard drives, but doesn't protect against a failed raid card, fire, flood, robber, acts of god, etc.
You can also look into zfs and truenas if you feel inclined. Be aware that if you go with this setup, ecc ram is basically a requirement