Majestic Book of Randomness

I need opinions for Hikari again

Sooooooooo I was working on planning out the worlds and plots for Hikari and stuff, and I realized that I gave Rob, Lachlan, and Mitch's group (R-L-M) one too many worlds, so I had to go back and change one (these weren't listed in the chapter before).

So the problem was, I have to take either Atlantica (the world from The Little Mermaid) or Halloween Town (the world from Nightmare Before Christmas) off of their route and move it over to the route for Jerome, Preston, and Vikk's group (J-P-V).

The thing is, I can't decide on which group gets which world.

This is basically another chapter where I ask you guys what you think.

I thought both worlds would be good for R-L-M's group, mainly because the Halloween theme seemed better suited for their group (plus they would all get Halloween outfits), but then again, I thought Atlantica would be funny for them because the whole colorful and happy care-free nature for that world seemed to be kind of ironic for that group (and plus they would all be mermen). (Mitch would really hate Atlantica)

But now I have to take one of these worlds and have J-P-V visit one of these worlds instead.

So, would you guys please comment what you think I should do?

I know it's kind of weird for me to ask for so much help, and you guys are probably getting tired of hearing this, but I really do appreciate it.

So, which group do you guys think should visit which world?  Which group becomes monsters and which one gets the fish tails?

(I will also mention that Atlantica will involve fighting Heartless and will have action, unlike the version from Kingdom Hearts II, which was a musical minigame world)