It depends on what drive is inside the external enclosure because ADATA doesn't manufacture hard drives. So it will be either a Seagate, Toshiba or Western Digital (or Hitachi, which belongs to WD now).
Personally, I would stay away from Seagate, even though I bought one three months ago (it had a nice discount and the price was too good to skip it). Besides this one, I have 7 WDs and 1 Samsung, and all are still good. But Samsung sold its hard drive division to Seagate years ago, so any Samsung HDD is a Seagate now. Same goes for Maxtor.
Use some software to monitor the temperatures and the SMART attributes, because high temps are usually responsible for HDD failures. Sadly, most of the external drives have plastic enclosures, and the temps will go up quickly in heavy usage. Those with metallic enclosures are not too common and are more expensive (usually LaCie).
I try to keep mine under 40°C. Avoid copying large quantities of data in one go. Copy something like 10 GB at a time, if you see the temp going above 40°C, then let it cool down for a few minutes. You can read more in
this article.
kbnrylaec: My suggestion:
Find the cheapest external HDD and buy twice.
Actually, I don't think that's a good advice. You can be unlucky and pick them from a bad batch and have them both fail. Buying two cheap ones from different manufacturers is a safer bet, I guess.
