Which NPCs like which biomes in terraria?

There's a happiness button in the housing menu that tells you what each NPC thinks of where they live, so trust that more than any list. That said, a few easy ones: Guide likes the forest, Angler likes the ocean, Dryad likes the jungle, Arms Dealer likes the desert, Mechanic likes snow, Wizard likes the Hallow, and the Truffle needs a mushroom biome to move in at all. Neighbours matter as much as the biome. Also don't pack too many into one spot, they get unhappy when it's crowded. Pylons only get sold to you if the NPC is happy enough, which is the main reason to bother.