The MyBooks are probably the last ones I'd look at. I've recovered data from serveral failed ones. But, of course, they have a fairly high market penetration, so it's hard to know if there's an unusually high failure rate.
In general, external USB drives have had a pretty high failure rate. Many folks believe that the lack of fans or ventilation in most commercially-built external drives plays a part in this. If I'm going to run an external drive 24/7 or use it for heavy-duty constant backups, I prefer to build my own in a high-end, well-ventilated housing.