I've used EZQuest, Maxtor and now MyBook (320) for imaging labs and handling data, and none have failed. I know someone with a LaCie that failed, and couldn't even be reformatted.
Out of the three I like the MyBook best--it's small, quiet and doesn't need drivers (like the Maxtor). I've read good things about OWC (Other World Computing) drives on a mactec forum, but haven't tried these myself. I think I would get one of those when I'm next in the market.
At any rate, always keep a duplicate backup of your external data (I keep a set on the office Mac's internal drive and a set on a second internal drive at home), besides archiving to DVD regularly.