When I first saw this thread, I figured the easy answer was that I would go for the Animal Crossing world because it's far more tame and you don't have to worry about Pok?mon, especially legendary Pok?mon, potentially wreaking havoc and destruction in your neck of the woods.
Upon further consideration, though, I think I have to give the vote to the Pok?mon world. For as potentially dangerous as it can be, it seems a lot more fulfilling and interesting. Sort of a high-risk, high-reward place compared to Animal Crossing's more calm and pleasant atmosphere.
Plus, certain Pok?mon would be nice to have in certain real world situations. Fire-type Pok?mon can help keep you warm or light fires for cooking if you're in the wilderness, especially in the Winter. Water-type Pok?mon can put out fires and can be useful for travel. Fighting-types, Ground-types, and probably Rock-types can help with physically labor intensive professions. Certain Flying-types can be used for short distance air travel. A Psychic-type Pok?mon like Hypno would be nice if you have insomnia and don't want to take sleep aid drugs, or they could probably help grab hard to reach items with their telekinesis. If need be, you can harvest the fruit growing from Tropius for nourishment.
As much as I love pokemon, I have to say animal crossing. AC seems like a much sweeter world that isn’t focused around trapping creatures with powerful abilities and fighting them nonstop.
Eh, when you look around and consider the regions the games are set in, it's not that bad. A lot of people aren't trainers, some are just working ordinary jobs like construction or in an office. Some Pok?mon help and work alongside humans with things like clearing land, or the Machokes in Ruby/Sapphire/Emerald/Omega Ruby/Alpha Sapphire who carry your boxes after you move into your house in the beginning of the game. It just seems like it's nonstop battling because the games center around the player being a Pok?mon Trainer and following their travels around whatever region the particular game is set in. Sure, there are gyms, island challenges, and Pok?mon Leagues, but some people aren't or might never have been Pok?mon Trainers. Some people have no interaction whatsoever with Pok?mon, and some people just have them as house pets.