Meh thats a matter of opinion, I am having a really hard time getting into on piece. Already 100 episodes in and definitely not as hyped about it as I was for Naruto at episode 100. To me Onepiece is to Dragonball Zish. I mean 90% of the show is too kiddy for me and at least with naruto they managed to keep it down to about 50% stupidity. Just opinions but we aren't there to debate which is better. To me nothing has gone wrong except that Kishi got in over his head with the war arc.
IT has gone on a bit long and hasn't felt really personal. But that was only the beginning of it, these last 6 months have been way better. Sure there are points when rules are broke or things that people don't like happen, but honestly this has always been the case. People are just more prone to noticing it when they get on these forums. And even if you have been around it is also a matter of age and personal preference. es the first half of the war arc was bad, but things are reall picking up speed and I don't see how anyone can complain about these last few chapters. If you are then TBH you are a whiner.
I actually think Naruto is vastly more childish than OP. To me, Naruto is a show for more angsty teens with a 12 year old's outlook on life, whereas One Piece is more of a show that adults can really get into with more mature themes. I'm 22 and I'll admit I'd probably like Naruto more 8-10 years ago, but I appreciate OP way more than I do Naruto at this point. I see Naruto all about changes in oneself, whereas One Piece is more about enjoying the adventure than self improvement. I think OP touches on much more mature subject matters than Naruto, and the pasts of the crewmembers and their flashbacks really show that. I mean is there anything more heartbreaking than the whole Nami/Arlong situation in Naruto? And you get that within the first 50 episodes of the show! And you haven't even gotten to he Water Seven saga which is in the mid to late 200s to the early 300s, which is even more sad and fascinating. I think you should really finish Alabasta to really get a feel for One Piece.
I will admit the artstyle is a bit weird, however I like it, though I do understand why some people might find it childish. However, when it comes to the story/adventure and the themes, it's far more mature, and I think it shows best when you look at the two main protagonists. Naruto has this 12 year old's outlook on life that if if you wish for it enough, there will be peace. Luffy doesn't give a f**k. Luffy understands the reality of the world and accepts it. Instead of going all emo and trying to change what can't be changed, he cares more about enjoying the ride. He beats up the baddies when he has to, but even after seeing all of the corruption in the World Government and the unfortunate death of someone really close to him, not to spoil anything, he doesn't go all "this world sucks, I need to change it even though it's a hopeless endeavor" like Naruto does. He continues on his quest to find One Piece rather than go out of his way to make these "changes". Even though we know Luffy will change the world, he doesn't make that his goal, it just happens during his adventures. I just respect that so much more from Luffy.
You're right though that this is my opinion, though I will make the bold claim that a lot of what I'm saying is subjective and not just opinion based. But, as I said before, One Piece might have a really crummy final stretch like Naruto has where all of is flaws get showcased, so I could have similar feelings to One Piece towards the end. However, I just don't see that happening at this point. But, yeah, I've really enjoyed the hell out of the past 3 or so chapters. I'm hating why Sasuke got any power at all, and I made a thread about it along with my opinions on the series as a whole, but some made replies that I should at least finish the series to make my final judgement, which I will do. I just think Kishi is falling victim to biting off a bit more than he could chew and is really struggling to tie the bow that connects everything together. I think that may just show his inadequate writing skills more than anything, but it's his work and he needed to do a better job with setup. But, again, we'll have to see the series finished before I can really confirm that thought.
This is all my opinion though.