As title says which in your OPINION is the best. Why do you think that way. ALSO I only have these three cause they are sorta the main competition BIG anime that most people have at least heard of
Sorry, Naruto takes the cake...
Naruto has been out since 1999 in Japan, so that's 12-13 years.
Naruto Episodes: 220
Naruto Shippuden Episodes: 245 (and still going!)
Naruto Movies: 6+
Naruto Video Games: A LOT
It's always been my favorite ever since the first couple of episodes on Cartoon Network. Even though I'm older now, I still watch it. The plot is always changing and the action is just really excellent.
One Piece has more movies, more than 10 already.
One Piece still has more episodes and is also still ongoing
Naruto has MUCH MORE FILLERS than One Piece.
One Piece(manga) started in Dec 24, 1997 & Naruto(manga) got published in 1997 too (Source from Wikipedia)