Most popular pony?- Twilight Sparkle is definitely the most popular in the fandom from everything I've seen.
Least Popular Pony - Out of the mane 6? Applejack. Out of EVERY character? I have no idea.
Best Mane 6 Member?- Rarity!
Best Villain? Including Equestria Girls and comics. - I can't decide, sorry!
Best Princess? - Luna! I also love Cadance.
Best Side Pony? - I love Big Mac!