Woah, her smile here is so adorable :3 .
Well, it's difficult for me to choose a waifu. I love all of the Mane6. Sweetie Belle is of course my instant fav, but c'mon, she's a filly xD. So my choice of my waifu will be... quite unusual, I think.
If I really had to choose, it will be her. I know that she's a background pony etc. but the receptionist pony from "Rarity Takes Manehattan" just won my heart. She has kempt, blond mane, lovely accent and her look in this pic... very cute . Imho she's very underrated character and it's a pity that there's not many arts with her . Fillies and gentlecolts, that's my waifu ^^.