Mucha Hawlucha, it's a way of life?
But seriously, I loved the damn thing the minute I saw it leaked a few weeks before XY's release. Aftering using one on my story team and one in competitive battling, I grew to love the thing even more, especially how it's already good speed get's boosted by Unburden. It's shiny's cool, how tiny yet brutal it is makes me love it even more, and it's fight scenes in the anime are just so much fun to watch.
Honorable Mentions: Ampharos, Chandelure, Entei, Gyarados, Swampert, Staraptor, Quagsire, Breloom, Furfrou, Lugia, Machamp, Cyndaquil and Jolteon.