I prefer playing with friends in all games, this one especially so because you really need to be switched on and communicating to have half a shot.
Pubs are pretty terrible as a rule of thumb but I have been in some good teams.
Most definitely zombies, anything else would just be an anticlimax for me. What better way to end the human race than by ushering a new breed of deluded, flesh-eating versions of our previous selves. Easily the best way to put Darwin's theory into action!