Seen almost everything of all of them. I stopped Bleach after Aizen and Naruto and OP a few months ago (maybe a year already) because Naruto was entering fillers and One Piece was really slow as always. I'm going to keep them on hold until they end.
(Ignoring the fillers)
Bleach is the worst one. Soul Society arc is very good, but the best one is the past arc, that is indeed excelente, specially because there's no Ichigo (terrible character, despite lijking him at the start). The rest was ok.
Naruto has the strongest start of the three, Zabuza arc was a good introduction and Chunnin exam arc was just excelent, after that is good. Shippuden starts badly, the firt two arcs have a really slow pacing, specially the second one which is very boring, then came Shikamaru arc and Pain, those were very good too, then it's downhill. The characters lose importance and it's all about Naruto and Sasuke. BTW, Naruto is not a story of the lower dog, Naruto e a genius, he just didn't know it, he's false and I hate him, specially after learning Rasenshuriken, he became OverPowered. Lee trained much more than him and deserved to be stronger.
One Pieace starts really bad, and while in theory is by far better than the other two, I can't rate it high because it has a really really bad pacing, it's simply terrible. Arabasta was my second favourite arc and was already slow, but then there's Skypea, Water 7 and Thriller Bark which are even worse! They go on and on and never end. My favourite arc was Sabaody, because they introduced many new characters and the pacing was ok. It's sad to say that my favourites episodes of One Piece ar episodes between arcs and the first few episodes of each arc, then it just goes on and on.
OP could have been reduced to 200 episodes with the same story and it would've been a masterpiece.
But they are all better than DBZ. Well, DB Kai was maybe better than Bleach.
Also, Fairy Tail sucks. Natsu is reduced to a character that either says he wants to protect Nakamas or is motion sick or is hungry, no wonder he's on my bopttom 5 worst characters. I stopped after 60 or so episodes, the only good thing is Erza and Gray, Erza specially is a very well made female character.