While they deal more with performance than reliability, I usually buy whatever is currently on
Storage Review's LeaderBoard for the appropriate category, or at least consult their reviews of the drives I am considering.
Like the endless AMD vs. Intel fanboy battles, no blanket statement about any hard drive manufacturer means much. Different product lines perform differently and can be more or less reliable -- you really should be looking at specific drives, not the manufacturer.
Seagate has a long history of making fast and highly reliable high end server hard drives, so they definitely know how to make a good drive. Whether they put the same effort and materials in low end products is another question.