Another vote for new.
On something like a computer where refurbishment usually means they swapped in whole, unmolested parts, I've no problem. I have a couple of refurb Dells from the outlet store now. On something like a hard drive where any refurbishment other than maybe reflowing a couple solder joints means cracking the case, I'm out. New drives are cheap. WD 2tb Blue, $50. Red, $79. Black, $113. Gold, $115. Ultrastar, $122.
A final aside... I'm inferring from your choice of drive that your data is critical enough to require enterprise-level drive reliability. If so, words/phrases like "refurbished" and "new old stock" shouldn't even be in your vocabulary.
Brad