The first hard drive reliability report was released by Backblaze in January of this year, revealing that Hitachi and Seagate drives are the most and least reliable respectively. Since then, the team at Backblaze has been testing more and more drives, updating their reliability report for September 2014.
With a collection of 34,881 drives storing 100 petabytes of data, Backblaze has a fairly good idea of which brands are the most reliable. Like they discovered in their January report, Seagate is still the least reliable brand, and Hitachi is the most reliable. However, they did record some interesting trends concerning some popular drive models.
The failure rate of Seagate's three terabyte drives has risen from 9% in the original report to 15%, while the failure rate of Western Digital models of the same capacity have also risen from 4% to 7%. Hitachi drives are considerably more reliable, with their 3 TB offerings having an annual failure rate of around 1%.
The single most unreliable drive in Backblaze's data center is Seagate's 1.5 TB Barracuda 7200.11, with an annual failure rate of 24.9%. You can check out all the failure rates from the 13 drives they tested with in their full report.
It's worth keeping in mind that these reliability figures relate to data center usage patterns, which don't necessarily correspond to desktop use. However if you do want the most reliable drives for your system, Hitachi seems to be the best choice.