probably Pokémon.... EEEEEVERYONE talks about it. Sailor moon is the most popolare at cons, like, in any con te see Sailor moon. my cousin told me that. so... ya... and Hetalia Axis Powers - Incapacitalia is kinda famous for its history and human countries.
Pokemon(my fav), One Piece, Naruto, Dragon Ball, Death Note, Attack on Titan, Sailor Moon, Bleach, Neon Genesis Evangelion … It's hard to state one anime. This animes are of different genres and also have different fans.