I think we all know who's going to win this poll......
On topic, Fennekin hand down. I think the idea of a fox magician is really unique and I really had fun using them. They're all so appealing in their own way; they've become some of my favourite Pokémon to date. Fennekin is cute, Braixen is graceful and Delphox is majestic (I won't lie though, I really think the hatred towards Delphox is unjustified. It does have a fanbase, but it's not as large as it's previous entries, so maybe the haters are just really loud....). The fact they broke the Fire/Fighting trend is plus as well; I was starting to get tired of that.
Chespin is the runner up for me. It was initially my least favourite, but they grew on me over time. Chespin has the cute factor, Chesnaught has the look of an ally you can defend on and Quilladin's derpiness is surprisingly appealing.
Froakie is my least favourite. I like this line, but I like the others a lot more. Frogadier is actually my favourite of this line, it looks sleek. I like Greninja, but I'm not obsessed with it like everyone else is. That tongue scarf really rubs me the wrong way. And Froakie is cute I guess.