Map:I like Hillside and the one based on it (the mushroom one, don't know what it's called)
Pricing: Double, I always like to build lots of different kinds of towers and that takes lots of money.
Gamemode:I've somehow never played a game with a special gamemode, so I can't say.
Armageddon:Can't decide, lightning's nice and easy and affects both sides evenly, but there's no way to stop it, it just continues until the end of the game.
Mob:Zombie Pigmen. They were my main xp mob before the update, and I still like them. Great for scaring noobs.
Tower:Summoner. They're not very versatile but I love seeing all the animals running around killing the mobs.