Just curious, which manga is most popular out of these three in sense of how many volumes selling, how many fans, and how many money made in marketing? It is hard for me to say.
Naruto
Bleach
One Piece
I already read naruto, I think it is so-so manga. I just start reading bleach up to 20 chapters, it looked okay so far. I did tried to read one piece several times but for some reason i keep dropping the manga and got into something else.
Please no biases, no favorites, just support your statement with facts and etc.

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512 essentials in 512

Well if you can trust wikipedia One Piece is winning by a long shot in sales of volumes, with like 230 million sold worldwide up to 2010. But in terms of merchandise and advertising Bleach is winning (apparently the japanese like figurines) Hope this helps

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Things I enjoy:

1. Badassery. I love being, doing, and living it. I also enjoy seeing it as it usually makes me cry man tears.
2. Badassness.
3. Badasses.
4. Badass mofos.
5. Manly badasses.

Things that I hate:
1. Wimpy protagonists.
2. Girly protagonists (if they're men).
3. Douchie protagonists.
4. Idiotic protagonists.
5. Over-the-line rude protagonists.

To elaborate a little bit. One Piece by large sells the most volumes of manga. It really has no competition in that regard. With that said, they've done some surveys and such which show that the average reader of one piece (Early 20s) is significantly older than the average age of people that read Shounen Jump (pre-teen to early teen). Because of this, the shows that they know they can sell more to the 10 to 15 year old crowd, tend to get more advertising and merchandising. This means Bleach and Naruto are much more prominently displayed.

Anything in Weekly Shounen Jump is going to be, by default, popular though. Just because its circulation is so high (double the circulation of anything else). Bleach, Naruto, One Piece, they all run in Weekly Shounen Jump. Along with Bakuman, Reborn, Beezlebub, Gintama, Sket Dance, Toriko, Medaka Box, Nura, etc. If you go back a few years, Weekly Shounen Magazine used to be very competitive with Weekly Shounen Jump. This was around the time it had School Rumble, Tsubasa, Air Gear, Fairy Tail was just starting, etc. But, since then, anything from Weekly Shounen Jump has just completely absurd popularity compared to anything else. At least if you only look at actual tank sales.

We're not talking about small differences though. We're talking about One Piece with like 3million copies sold. Naruto, Bleach, Bakuman at like 1million copies sold. And everything else at <300k sold. There's a few random outliers. Shoujo series like Kimi ni Todoke and Kuroshitsuji. There are also things that spike in popularity for short periods of time. For example, things nominated for awards or that get anime will shoot up. After the Manga Taishou announcements, March comes in like a Lion and Shingeki no Kyojin shot up over 500k per volume. But, previously I don't even think they ranked in sales at all. Similarly, Ao no Exorcist shot up to over 500k per volume after the anime started. Its also hard to compare it to series that have already ended. Like Dragon Ball and Full Metal Alchemist are still super popular, but what metric would you use to measure how popular they are? FMA was one of the few manga outside of Weekly Shounen Jump that could break 1mil per volume. Things like Fairy Tail don't even break like 500k.

you can go to pages like

http://www.oricon.co.jp

http://www.oricon.co.jp/entertainment/ranking/2011/bookrank06 01/index06.html

and
http://www.oricon.co.jp/rank/obc/w/2011-08-22/

One Piece
wins


btw
you should force yourself to read the first 40chapters or so of one piece
they are boring and bad
as soon as the team is starting to form it becomes great