Yeah they're both good. Seagate owns Maxtor, which is a crap brand, but luckily the plain Seagate ones are good. I have both in my computer and they are both fine. No problems at all...
I also heard WD hard drives overheat and some external hard drives aren't that good.
It's all good though, Samsung also makes 1 or 2 hdd's which I've heard are good but the big brands are WD and SG. Just like AMD and Intel.
EDIT: But these could be all rumors, most likely are...