This is actually a pretty tough call, because I like a few of the lions about equally. I'm a big fan of Lionel's design because it just looks dapper. Elvis has the traditional look of a lion that one would expect, which is a plus all its own. Then there are Bud, Leopold, and Mott, all three of which I love because of the glasses they wear which give them that little extra something over other villagers.
Narrowing it down, it becomes a three-way battle between Bud, Leopold, and Mott. Bud has those unique sunglasses, Leopold has a pleasant color scheme and cool green hair, and I learned to really appreciate Mott after he lived in one of my towns and moved out, and I just recently reacquired him. Plus Mott's name makes me think of apple sauce, so hey, nice.
I think I overall like Leopold's design better than I do Mott's, but as of the current moment I have more built up affection for Mott because I had him as a villager previously. If I ever feel like replacing him in my town again, we'll see, I might bring in Leopold in his place.
As far as the poll is concerned, I guess I have to give it to Leopold. As much as I like Mott for sentimental reasons, as expressed above, Leopold just has a more agreeable design to me at the moment.