Well prince pf ersia is a great series, no doubt I played it alot on the ps2 and loved it..melee moves and killing giants and bosses were awesome, got very good ratings so I would get it..but then l4d, is a great game as well ok graphics and very good gameplay.. if I would choose it would be Prince of Persia because it got great ratings, and has a very nice series.
I say LEFT 4 DEAD this game doesnt have the greatest graphics but the awesome gameplay makes up for it. I will agree that POP's graphics are a little different this time around, it is fun but overall Left 4 Dead is a better decision.
trust me mate get left 4 dead (or i recommend dead risin) prince of persia is filled with good combat and lots of good areas but it lacks point on the other hand left 4 dead has battles round every corner as zombies come after you all the time there is more interaction with your surroundings and has awsome graphics but there is another game called dead rising you start in a mall (supermarket) and zombies are everywere not only do you fight zombies you fight loony humans and you can interact with every thin in the game you can even barricade doors (if you have it i suggest the gun shop barricade door and smash window duck behind window and start firing or grab a trolliw and pack it with guns food and stuff