Hello all,  I have a 36 Bay 4U Rackmount Server that i am setting up as a PLEX Media Server.  I have mainly had experience with WD Red drives, but I honestly don't know which drive is best for this size of an array.  The new Iron Wolf Pro drives look promising, but I have no experience with Seagate drives.  Any input would be appreciated.

Size of the array doesn't really matter. You will find fans of any given brand of drive, and just as many who think a given brand is junk.

Some of the people here consider their Unraid setup from best-in-class perspective and use only "enterprise" hard drives.

I think many are like me and buy good deals, whatever the brand.

In the end, I treat all drives exactly the same. I run pre-clear a minimum of 3 times before I put it in my array; I always have a spare drive that has already been pre-cleared sitting on the shelf and I run 2 parity drives. That gives me peace of mind (generally speaking) and, in theory, enough time to recover from a failed drive. Perhaps I've been lucky, but I've only had to make use of my spare drive once in the last 8 years.

Whip

 

Enterprise drives are claimed to have better vibration resistance, and in a 36 bay server it might make a difference, or it might not...

 

If it were me I wouldn't worry about it too much.  Just buy the flavor you like that you think will be reliable. Wd reds are good drives and should work fine.  I've got about 10 of them in my server and they've been flawless for me so far.