You're definitely not a hipster, One Piece is as mainstream as it gets
I haven't seen Blue Exorcist, but for what it's worth I'd say Soul Eater has a fair bit of awesome characters, great fights (fantastic animation!), some emotional depth, unique designs and an interesting overlapping world. It drags on, though, as do all shounen in my experience, and I couldn't find myself caring much about the second half.
For recommendations I really think MAL
are much better, because they have people who are actually knowledgable about anime and can recommend a niche anime that came out 10 years ago that might fit your needs better. Especially the MAL forums, they give thorough customised recommendations.
Full Metal Alchemist Brotherhood (dunno if you've seen it?) seems like the best bet if you want something like the description you gave of One Piece. It's such a masterpiece among shounen shows. And since One Piece is half comedy, Gintama might work for you too. That being said, I can't really stand shounen anymore, so I'm better off recommending stuff in a genre completely different from young-boy-gets-stronger-and-fights-spectacular-battles-for-fate-of-the-world.
And man, I haven't seen anime in forever
. Well, sort of re-watching Ergo Proxy with the gf but at a really slow pace.