I used to really like Seagate drives - for a while there, they were the only ones with 5 year warranties. But, as Jon says, some models have been having some serious reliability issues lately, so my allegiance now goes to Hitachi and Western Digital. A good source of reviews (and drives - their prices are usually among the best) is
http://www.newegg.com - I
always check there before buying, even if I end up buying elsewhere - which for me is usually my local Canada Computers store, which is often just as cheap, with a further discount for cash.