There aren't any independent statistics or tests available on hard drive reliability. The best anyone has to go on is anecdotal evidence or things like tallies of complaints on retail sites. None of that is really reliable because you only hear about the problems, not the successes, and because it's hard to tell if more complaints = more problems or just more drives sold.
My advice is to not worry about reliability - any and all hard drives will fail sooner or later. If your data is important then you need to back up your data even if you knew for sure you had the most reliable hard drive in existence.
Instead, focus on performance, features and cost and base your decision on those factors.