HGST drives are rock solid, a bit noisier than some but absolutely rock solid. I'm not a brand loyalist but for the time being I don't see myself buying anything aside from HGST when it comes to spinning rust.
I've been happy with Western Digital Black and Raid Edition drives as well. HGST NAS line of drives have provided better $/tb for new drives, and the all-but-identical Ultrastars offer fantastic value. Both HGST NAS and HGST Ultrastar have been rock solid.
The only cheaper drives I ever see are Seagate, and the failure rates on those are atrocious. Any chance we get we are taking any Seagate Constellation or Seagate Barracudas out of service permanently, even if there is no obvious problem with a specific drive, due to the massive failure rate of both models. Have something like 100 of them lying around which have passed SMART testing after a dd wipe. We had been thinking about selling them, but now am looking forward to mining burstcoin on them = P
To put some numbers to it, yearly failure rates are something like 0.3% HGST, 1% Western Digital (Black and RE), and at least 10% a year for Seagate.
Other Western Digital drives are not so great: WD Blue drives, in my opinion, should not be used for any purpose, similarly to the Seagate Barracuda drives. WD Green drives also leave much to be desired but are at least reasonably reliable.