My least favorite just has to be Aftermath, it's a similar map to the modern warfare 3 one, I can't recall the name actually though it sucked pretty bad.
My more favorite map though, is encore. It has such a cool and amazing style to it. I really enjoy playing on it, and even though most people just choose a different map - It's because they hate it. I still choose it, it has so much camping potential, and securing positions. As in, playing with a battlefield style, not just rushing. More like a... Run and gun camping style.