I like plastic cards, for their feel and their durability. Paper cards are just a dollar a deck, and easy to replace, but they get an awful swollen grubby feel as they age, and their corners get docked, and so on. You can find paper cards in a much more charming variety of vintage designs, though.
I'm fond of Kem cards, perhaps the most popular plastic card, but this poker site has opened my eyes, with evaluations of various plastic cards according to numerous criteria, including how loud they are when shuffled and the size of their pips. I'm not that obsessive, not yet. I do want to try out a set of sturdy Dal Negros, I think (brown/green Superstar backs, regular index, if you're looking for gift ideas).