I think I know how you feel...
I just fell in love with Naruto, which I started in 2007 (or 6? idk). Watched the anime and then got caught up with the manga. It was all some of my college friends used to talk about.
As for One Piece, I kept myself away from it for years because it never grabbed my attention, regardless of the manga sales.
THEN, in 2012, one of my uni professors told in his introductory class that OP is his fav series. So, I decided to give it a shot. And... I haven't dropped it ever since

I cannot believe that I once actually said that it wasn't worth my time. I mean... Hats off to Oda, that is all I have to say. I just like his way of storytelling. It's brilliant.
As for Naruto, I still haven't dropped it. We have a weird on and off relationship... I dislike the way Kishi handled the current arc but I kind of want to know how it ends. I don't feel good when I read it, but still I wait for a new chapter every week.
I think Naruto has a great and quick start, while One Piece takes some time to pick up (Nami and Arlong history etc.) but it's worth it. Its 747/8th chapter came out this week and, I am not exaggerating, it still never ceases to surprise me, which is extremely rare for a series that long.
PS: I'm caught up with both of them... So, don't think I'm judging them prematurely. n__n