Which Enterprise Class HDD? Or not necessary?

Hi all,

I'm curious what everyone's experience so far is with various options of HDD's with current release FreeNAS (11.3) and ZFS in general.

I'm genuinely curious about the following:

Enterprise class:

Ultrastar/Gold (WD, HGST, Hitachi) vs EXOS (SG) vs MG (Toshiba)
I was seeing a different in how SG outputs SMART information. Does this really matter?
Is it truly worth using enterprise level drives in a system with mirrors (no parity based redundancy)?

Reliability...

Which Enterprise Class HDD? Or not necessary?