Other maps I hate include: Bootleg, Village, Mission.
Bootleg: I hate Striker people.
Village: I'm all for big maps, but this map has too many useless areas.
Mission: If you spawn at A, you are screwed. The map is extremely imbalanced with the high vs low lands. If you are trapped at A, enemy team can just sit at the top and pick you off constantly.
Downturn- there's absolutely no flow to this map, and even with 'improved' spawns, it's just a clusterf*ck no matter what gametype. Second place goes to Carbon for having just an awful layout. The team at the bottom of the hill is funneled through just a few tiny chokepoints with no real cover. Any decent team can trap the enemy at the bottom of the hill for the duration of the match.