Personally, I think they're both good shows. Adventure Time is good because it's very imaginative and amusing because it's so bizarre. MLP is good because it's witty and has very stylish animation. MLP does have the deeper characters though. Finn and Jake are kinda two-dimensional (no pun intended), they do the same thing in every episode and you don't really ever see any other sides to them or their back story. MLP does give it's characters different sides (i.e Pinkey has a hidden complex about the idea that people might not like her) and also gives them back stories (i.e Rarity grew up in a small-town, but tries to hide this fact by acting and behaving in a high-class manner).