Third... And Rather long in its time of demise. Is zf_lumberyard_v17. Although it was balanced with removing the central sentry gun, its still an unbalanced map for survivors, only now its the zombies that gain the balance, as the ability to destroy the main source of healing and ammo for the survivors, and they all they have to do to get 'easy pickings' is destroy both the big doors that keep the survivors safe, although the energy barriers do help, its easy for a large swarm of zombies to merely overwhelm WITH VERY LITTLE CHANCE at survivors being able to hold off just because their health and ammo are literally now DEATH, by pit. Combine that with a rather ludicrous time limit, and... Ugh. Its just bad.
Then we have the BIG ONE. The Granddaddy of all this stupid shit. I'd say Alpine, but that map... its a fun map, despite my hatred of it, this one is much more pressing than the map that actual teamwork can be done with some ease.
I mean zf_dustbowl_b4. And it's not even the worst offender. But its number 2 for a reason. The map is so heavily unbalanced in the favor of zombies its not even funny. It takes teamwork beyond what can be expected of nearly any GOOD, not great, but good at the game and ZF in general, player. The Zombie Spawns are everywhere, the time limit is decent, but there are too many control points, insanely long capture times, and the zombies rarely have a problem, even with friend medic pairs.
*continued in third post with the final offender.*