Hmmm....I would go with Luigi's Mansion Dark Moon. I had way more hype for that game and its always fun playing it. I have Animal Crossing New Leaf and its great as well. Though, they're both kinda different...don't you think? A bit hard to compare.... New Leaf feels a little too much like the older games, while Dark Moon is very different from the first. Dark Moon vastly improved from the first game and New Leaf added things and improved in some areas.
I play mostly on the 3DS. My 3DS FC: 0387-9566-9545 Name: Chip
I got luigis mansion a couple days ago and..... its kind of slow an boring, go with animal crossing, i wish i did cause LM is boring, you just walk around the same mansion for a worlds worth of levels, then onto the next "mansion", if you had nothing to play then luigis mansion wouldnt be that bad, but against animal crossing it loses big time