This is the story of Luffy, a 17 year old boy who wants to become pirate, but in order to do so in the great pirate era, he must find One Piece, the treasure left behind by Gold Roger, the previous pirate king!
Luffy is a super rubber man, powers granted to him by the gomu gomu devil fruit. Devil fruits are rare and mysterious fruits found all across the world of One Piece which grant its consumer powers in exchange for his ability to swim. With this strange powers granting him unortodox fighting abilities. Luffy goes from place to place gathering members for his crew, facing opponents like Buggy "The Clown", Captain Kuro, Don Krieg, "Saw-Tooth" Arlong and Captain Smoker. Once he finds nakama in Zoro, Sanji, Nami and Usopp he sets for the Grand Line! The Grand Line is the sea in the center of the world where the strongest men gather, making Luffy rapidly face even greater foes like Sir Crocodile, God Enel and the CP9. Eventually Luffy becomes part in a war which will decide the future of the era.
Part 2 - New World:
After navigating through the Grand line the Strawhats discover that they are still small fish in such vast waters, and after being separated decide to train themselves to be able to face the challenges that they will face ahead. 2 years pass after the events of part 1, and the Strawhats reunite back where they where seperated. Each having great growth through there efforts over these years, they head to New World, the 2nd half of the Grand line and most dangerous ocean in the world! After reaching facing Fishman island and saving it from Hody Jones, the Strawhats finally make it to New World, which is full of dangers and enemies more dangerous than anything theyve ever faced before.
One Piece verse has good speed and strength, strongly influenced by Dragon Ball, it has had huge growth in power over the years. Pretty much every fighter in One Piece is a bullet timer, and most have huge amounts of physical strength, having feats like Arlong being able to rip out and toss houses ever since the first saga, and catching cannon balls in his jaws and crushing them. Despite this apparently impressive feats, they are in reality insignificant to current OP fighters, most having millions of tons of strength and at least massively hypersonic speeds, some feats as far back as Skypiea showing impressive deeds like Luffy lightning timing a lightning bolt to kick it out of his way. Currently top tiers of the verse are 4 digits and have billions of tons of strength. They are also capable of contending with, or are island busters, and some are even higher than that. Even the lower tiers which dont have much strength or speed tend to have quite high resistance to blunt force trauma, like Usopp who got hit by a 4 ton hammer being swinged at super speeds even back in the second saga of the serie.
One Piece has 2 specific weaknesses though, no devil fruit user can have even half his body covered by water or he'll lose all his strength, and most characters dont have any noteworthy durability to cutting and piercing damage. However this is mostly compensated since there are strong characters that dont rely on devil fruits, and strong devil fruit users which can negate cutting and piercing with there fruits powers. Furthermore, cutting and piercing has become even less useful, since pretty much anyone notorious in New World knows how to use haki. One of the many uses of haki is called armament haki, which fortifies anything the user wills, thus making it much harder and stronger.
Not only does OP have superior speed and physical strength in comparison to most all of Bleach and Naruto, it also has far more high tiers. OP is not to be made light of, it is an incredibly vast verse as its aproximately 800 chapters of content prove. And One Piece is far from finished, it still has several more years till its done according to the author, so it has vast room to keep growing. Finally, pretty much no known top tier of the verse has gone anywhere near all out yet, let alone the absolute peak of the verse in power, so One Piece will still become vastly stronger than it currently is. It is worth noting that the only top tier whos gotten serious was WhiteBeard, and that was while he was a sick old man fatally injured and that didnt use haki because of serious Plot Induced Stupidity. And even then he was still holding back in his best feats due to concern for his comrades, with all this he still managed to do feats which are potentially country level, so OP still has a lot more in store for its future growth.
OP's greatest downfall at the moment is that its top tiers have barely any noteworthy feats and thus this currently ranks it under Bleach and Naruto thanks their top and God tiers.
Calcs, Feats, etc.
Lightning timing One Piece beggining since low tiers:
http://i.imgur.com/JmK7zI1.png <(Upper left panel, Luffy kicking lightning away)