I didn't hate anythhing bad enough to get rid of it, but if i had to i'd say halloweentown, since the story was pretty weak there in KH2. I'd keep Atlantica as maybe a mini world if your going to do the music(which I kinda like since it brought me back to my days playing UM JAMMER LAMMY), but if they bring back the swimming around and fighting properties to the world. They will need to really work on the mechanics of it, swimmming in KH1 was probably one of the more frustrating things to do in KH1. as for 100 acre wood, I'd keep it, it's a nice spot to relax and kill sometime if you need a break from fighting a boss or something. Agrabah, give me a story and fix the mechanics to the carpet riding. As for Sephiroth, he has gotten a tad bit stale, he's lost the essence he once gave in FF7, ya know the whole oh god help me now its HIM vibe he used to give off. Personally I'd like to see them bring in another FF boss/char instead of Sephy for the FF optional boss of KH. Maybe Ultima Weapon, Odin, That dude that tried to marry Yuna(his name escapes me at the moment) with his Aeon obviously, Ifrit, Bahamut or Shiva would be cool.