Hmm. Well for good Survival Horror I would play Resident Evil 4 (One of the greatest games ever made.) Arguably not zombies, but they come close and you definitely feel like you are surviving a viral outbreak.
Another would be Dead Space. Space Zombies at their finest. That game is terrifying and holds very true to the survival horror genre. Constantly being low on ammo and the dark environment of a derelict ship is perfect for this type of game.
Left 4 Dead you have already played. So I would have to recommend the Zombie mode on either Call of Duty: World at War or Call of Duty: Black Ops. It's a very addicting game mode that pits you against an endless horde of zombies in a wave style game play.
And for a bit of fun I would recommend Plants vs. Zombies. Very colorful and fun game. So addicting.