It would be hard to imagine getting anything other than anecdotal replies ("I've owned 3 LaCie's and they are great!" or "My LaCie crapped out after 2 days and lost all my data", etc.)
Both are bigger brand names which is a plus. I don't know what drives LaCie uses in their externals, it might even be Western Digital!
Make sure you get one with Firewire though, rather than USB-only.