Heh. xD I honestly doubt it'll become a big thing, it'll be big for the first month or so (similar to Miitomo) but eventually fade away into obscurity as that one thing Nintendo did.
At the moment, Moon, if only because I prefer the Legendary, but I'm still waiting for game-exclusives to be revealed (or at least a couple to be revealed?) before making a solid choice. Also, yes. I'm excited they're bringing back customizable characters....I just hope I can find something that fits my general style like I was able to with X/Y.