As far as sales per year go, this is the ranking for best selling mangas of all time in Japan:
1. Dragonball Z
2. One Piece
3. Naruto
4. Slam Dunk
5. Bleach
Since DBZ is no longer in production that would make One Piece the current #1 manga and Naruto in the #2 spot.
Ok
There is so much wrong with this post.
First, One Piece is the number one manga in Japan.
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Compare it to Dragon Ball. One Piece is almost double of what Dragon Ball has sold. Naruto is way lower then that. Next, your list is way off as you can see according to the image. You missed Kochikame and Slam Dunk(for those who don't know what they are, they are pretty good. They deserve their rank.
Now, if you want to make the argument of not Japan and do world wide, I give you this link.
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That one actually shows Dragon Ball as number one and One Piece as number two. Again, most of the order is kept and you are missing manga's in your list.
Lastly, the last line you wrote. Just because a manga stopped being in production doesn't take away everything it did. Dragon Ball deserves everything it has done.
OT: Naruto has some references to some Japanese mythology, but does that make it the reason it should be the best? There are others that have amazing art in it as well. Some of them are really unique, some of them are done with computers, but I don't feel that should make a manga be good as well.
The story should be what is important. Naruto's storyline is good, but there are better. Of course everyone's opinion on what a good story is and why they like in a manga differ. This makes it figuring out what is the best difficult. Imo, i feel One Piece has the best storyline. Full Metal Alchemist: Brotherhood has a really good storyline too. Tbh, this is a hard question to answer what is the best.