I'd have to disagree: Dark Carnival is just pure brilliance whether it be roller coasters, the strangely long tunnel of love, fairground games then a freaking Rock Concert finale. it's an absolute work of art except for one thing. GNOME CHOMPSKY. I hate him SO MUCH. EVEN MORE NOW I HAD TO SAVE HIM TWICE. him and his smug smile...staring at me as I get mobbed by zombies...*shudder*
Hard rain is still awesome though, the effects are stunning and it's laid out extremely well, not to mention it's the first time in ages I actually got real tension in a L4D campaign. It's certainly fantastic, but Dark carnival will always be my one true love. Except the gnome. You could probably convince me hard rain is better solely due to lack of a gnome. But I won't let you!
Dead center's really well done as well, Swamp fever I haven't played enough and the Parish is good, but I've played the demo a LOT so two maps of it are already tired for me.
I'm really enjoying going through trying to find all the clues to the infection and what's going on, this game is amazing.