Personally, I'd prefer it if the game was more about surviving the zombie outbreak itself rather than saving/looking for some hot chick/family member/random child OR fighting your way out of the city to a happily ever after because there happens to be zombies only in the city you are in OR fighting your way INTO the city to uncover the hidden truth behind the reanimated dead (normally some sinister government body) and then vanquish the Big Bad because you're stupidly heroic that way.
Games tha have "Survival horror" tacked on are appearing more and more like, "Here, have an action game, we're just going to dim the lights and send these screaming monsters at you instead of enemy soldiers." It's disappointing.
Oh! Good zombie AI and variety. I'd love to have myself be torn limb from limb, then come back from an earlier save (if that option is allowed) and not have the ability to go, "Okay. This is where # number of zombies pop out from here, so..."
Someone mentioned a skill tree and I agree wholeheartedly. Start off as the Average Joe and work your way up. I don't know about you lot, but I don't happen to have a shotgun hanging over my bed and the accuracy required to shoot zombies in the head with a side arm. Which I also don't have.
The ability to find other survivors, stab them, hang them from a lamp post and use them to draw undead attention as you sneak away.
Laughing gleefully whilst you do it.