The most important feature of an HDD is definitely the reliability, which unfortunately is not easy to measure. Most of the tests indicates that Western Digital are the most reliable over time, and so they are our first choice. The performance difference between Black and Blue series is difficult to perceive in everyday use, therefore we recommend the latter as it's cheaper. The Seagate Barracuda are less reliable (but still good) and have better performance than WD, so they are a compelling alternative.
We also have created a HDD performance chart where you can find, filter and sort the best drives the market has to offer.