I can't really tell you what is the "most reliable" HDD in the market because everyone has their own opinions towards the HDD they are using. Back when I was in college, about 10 years ago, we debated on which is the better HDD, Seagate or Maxtor. Now that there are other companies that are creating HDD, then the debate grew bigger.
I have used 4 different brands of hard disks, Seagate, Maxtor, Samsung, and WD. I currently use Samsung and I'm sticking to it for now. There is one time that I would defend Seagate as the best HDD but that is already the past for me. I'm open to any new hard disks that will be sold on the market today.