I would play more zps, but I could never get around the fact that it felt like a larger shittier version of Left 4 dead.
:l It's not like L4D at all really, I don't believe ZPS ever gets old due to NO AI at all. L4D and L4D2 got boring after a few weeks, and I only play if friends invite me, and even then it kind of bores me. L4D offers the same linear levels with seeminly random zombie spawns, and linear based objective that get harder based on difficulty and the other random things L4D added. While ZPS offers human v human levels that range from linear objective maps, non-linear objective maps, time limit objective maps, survival maps where zombies have X amount of lives and the humans have to survive, and then we have fun custom maps like dodgeball and deathruns. There's even more than that, such as ZPA where zombies and humans have to capture different spots on the map, earning them extra carrier zombies or weapons, etc. ZPA mode was kind of a dumb idea but some people like it, then there's ZPH, hardcore mode where zombies have 90% infection and weapons deal less damage. Humans just have to survive 5 minutes. I have 2400+ hours on ZPS, and less than 200 on L4D 1 and 2 combined. Clearly I prefer one over the other, which is why I'm a head admin, but from my experience I'd say ZPS is the coolest.
It's quite different, I wouldn't say it's bigger and I suppose since L4D has made hundreds of thousands of dollars it probably more played, liked and "better". Especially graphically. I prefer ZPS for it's playability though, endlessly capping retarded AI zombies in L4D gets old, where in ZPS every zombie has it's own skill level depending on the player. Some zombies like I know how to spin around and avoid bullets, where others walk in straight lines making headshots too easy. I really enjoy playing Zombie and destroying the human team, I'd even say zombie is overpowered but people always complain about getting Zombie and don't even try... There are many different servers that offer different gameplay styles and sometimes you just have to find the type of map you like. Some people prefer cabin/lake maps and barricading for 10 minutes while I prefer doing objectives and leading a team around. Basically the game is ALWAYS different because you spawn with different people, different zombies, so what people choose to do is always changing, giving each map gives you enough options.
Yeah.. but anyway saying L4D is better than ZPS in any ZPS server causes mass rage. Most people will defend L4D as a good game but everyone agree's it's not as replayable and that ZPS offers much more fun and lulz. It's a hell of a lot prettier, but like women, beauty doesn't ensure a long, happy relationship.
I prescribe a heavy dose of ZPS, that should clear your botched opinion of the game right up!