I like Seagate's because they have been very reliable for me (I am running about 5 of them right now.) Also, most Seagate's come with a 5 year warranty.
Western Digitals have also been pretty reliable. I'm not sure about their warranty, but I think that it might be between 3 and 5 years for most of their products.
Maxtor's have not been reliable for me. Also, most of their warranties are only good for one year, which stinks. The redeeming quality is that their customer service has been excellent when my drives have failed within the one year period.
I forgot to add Hitachi. While they have been pretty reliable for me, I did have one of their laptop drives fail recently. Their RMA process was VERY SLOW, and they would not do an advanced RMA. So, I had to buy a replacement drive in order to make my computer work. Otherwise, I would have had to gone two months without a drive in my laptop.