Better then Left 4 Dead
LEFT 4 DEAD - Pros over Killing Floor
What is better about L4D is that when you are the humans you can play against other humans/friends.Graphics,Microphone volume and the ability to be the infected/zombies all go to L4D.
Killing Floor - Pros over LEFT 4 DEAD
What is better about KF is everything else.Tons more weapons and tons of different bad guys/girls to kill.You could heal teammates or seal doors instead of shooting or slicing.Both can be the difference in winning or losing.If I'm playing as the humans I would prefer KF 90% of the time over L4D.The price was $15 on steam and I paid $30 something for L4D a year or more after it came out.
Killing Floor- Cons
#1.You can't hear your teammates clearly or at all at times.Even with the in game setting at max you wont be able to always hear or make out clearly what your teammates say.I was told to buy a headset and clearly that is the answer.Many people just type only.
#2.You can't play against humans/friends or as the bad guys/girls.This is why I might prefer on a rare occasion to play as the humans on L4D because I can play against friends I know personally.
#3.Graphics are a few years old.This didn't bother me at all but it is a con of the game.
The Bottom Line - I highly suggest you buy both games but I give a big edge to KF when it comes to playing as the humans.When I play as humans in L4D it is fun for 10 minutes or so and then I just want to be the infected/zombies for the next hour.
My 2 cents