One Piece is my 6th favourite anime/manga series.
#1 - Gintama
#2 - Berserk
#3 - Kingdom
#4 - Hunter x Hunter
#5 - Attack on Titan
#6 - One Piece
I'm planning to start numerous manga soon, like Monster, 20th Century Boys, Vinland Saga, Toriko, Magi, Haikyuu, Hajime no Ippo, so who knows if One Piece will even be in my top 10 when I'm finished with all of those series.
I'll always love One Piece because of a nostalgic connection I have to the series, but I think the quality has dipped quite a bit over the last few years. I don't love the series like I once used to.