I must be alone in loving The Parish finale. The first time we played it was on Advanced Realism, and it was just beautiful chaos, trying to work out where someone had been charged or jockeyed based on their vague instructions. Only two us made it across the bridge proper, and then I died staggering toward the chopper (I was greyed and limping; it was awesome), so one guy pulled us all out.
I just soloed that Bridge Over Trebled Slaughter achievement, too.
That said, my campaign ranking is:
5. Dead Center (wonderful opening level, fun finale, but the mall map is the worst in the game, and seriously underwhelming given the potential there).
4. Swamp Fever (beautifully spooky, but a certain lack of variety kills it; on the other hand, it has possibly my favourite finale, both in looks and execution).
3. Dark Carnival (the variety and hilarity of detail here puts the mall level to shame, and while the finale is fairly standard to play, it has the most flair of any L4D map, past or present).
2. The Parish (the purest L4D experience, I think, with its winding urban environments; the cemetery map is one of the best long haul levels in either game, and the game's closing finale is suitably demanding and enjoyable).
1. Hard Rain (some of the most inspired and atmospheric level design I have ever experienced, and probably the best use of weather effects in a videogame; that first run through, Realism-style, was the standout highlight of my gaming year; only the finale is somewhat disappointing).
