I think Luna breaks the contest rules since she is an alicorn (an unfair advantage - similar to Hercules in the series on which he was tested for "half god positive")So between Twilight and Rarity...I say Rarity... she sure put a lot effort into her appearance!(Also i dont think having an "study session" with her sure isnt as exciting as it sounds...)BUT...that all is just theoretical since: there is NO best pony... you have to love all of them equal! (ofc you can have your favorites...)and thats why i deserve to take all 3 with me