I personally don't see that many people hating on Popplio. There are some but it seems that most just prefer Rowlet. It feels weird for me now that my favorite is the popular one. I mean first there was Bulbasaur, the last couple of games they were Chespin and Tepig, each of which seemed the least popular of their trio. I just go with what I like. That being said, I personally prefer Popplio over Litten, but I really like all three.