It is evident that the only person capable of surpassing Roger is Luffy. Even though Luffy still has a lot to achieve, he is the only person who can transform the entire world.
Roger would come out on top. Roger was known as the Pirate King and was considered the strongest pirate of his time. He had immense strength, speed, and agility, as well as the ability to use all three types of Haki (Observation, Armament, and Conqueror's).
5) Shanks. While Shanks' combat skills are seen very sparingly throughout One Piece, there's little to no doubt he's stronger than Luffy and could defeat the Supernova.
Famed throughout the world of One Piece as "Whitebeard," Edward Newgate was the strongest man in the world right up to the moment he died. Thanks to his incredible Devil Fruit powers and Haki, he was nigh unbeatable. Even the Pirate King, Gol D. Roger wasn't able to defeat Newgate in battle.
1 Whitebeard, The World's Strongest Man
Captain of the Whitebeard Pirates, Whitebeard was one of the strongest pirates of Roger's time. With the power of the Gura Gura no Mi and an incredibly strong Haki, Whitebeard was known as the strongest man alive. The only person strong enough to equal him in combat was Gol D.
Roger could possibly beat any character in the series. Although he isn't alive right now, he did clash with Kaido at God Valley where the Rocks crew was annihilated. Arduous as it may be, it is expected of the Pirate King to be able to take on Kaido without much trouble.
Roger was the epitome of the greatest Haki user as he possessed all three major Hakis known in the world of One Piece. He was the captain of the famous Roger pirates, which consisted of powerful people like Rayleigh, Shanks, Buggy, and many others.
Currently, Kaido is the strongest pirate alive in the One Piece world. However, eventually, Luffy will go on to surpass him and even surpass Roger, Whitebeard, and even Rocks to establish himself as the strongest pirate to ever live.
Roger's first and perhaps his most formidable rival and greatest enemy was Rocks D. Xebec, the captain of the legendary Rocks Pirates who sought to become the king of the world.
Garp is known to possess immense Haki and as fans know, he does not have a Devil Fruit ability. As such, fans will most likely see the level of his Haki power in the upcoming chapters of the story where he clashes against Yonko Blackbeard.
Kaido is one of the best fights that fans have seen in One Piece over the years, if not the best. The fight is, undoubtedly, the most difficult one that Luffy has fought so far. Kaido managed to defeat Luffy three times. For the first time, Luffy faced defeat against him Kuri and was thrown in prison.
In Road To Laugh Tale, it is revealed that Luffy's true power is not his rubbery physiology, and instead something much different. In truth his power allows him to bring forth whatever he can imagine into reality, however, this is only possible if the Devil Fruit awakens and is limited to Luffy's own imagination.
Currently, however, Shanks is likely stronger than Luffy, simply due to the fact that the plot demands that of him. Luffy has not surpassed Shanks just yet, otherwise, their future fight would hold no significant value.
Points: Zoro 1, Law 0 Devil Fruit Roronoa Zoro is a very powerful character. He is known as one of the most powerful characters in the series and one of the series' best swordsmen; he is, by all means, probably going to surpass even Mihawk in the future.
If Zoro is considered Luffy's right-hand man, then Sanji is his left-hand. As a future Pirate King, Luffy relies mostly on these two during the most crucial times. That said, Zoro and Sanji's relationship isn't considered the best in the series.
Although Roger hasn't been seen fighting in the series so far, people who have watched Roger fighting label him as a monster. Only two people are known to be on Roger's level — Whitebeard and Rocks D. Xebec. Shanks hasn't displayed his true power either, but it probably wouldn't be enough to beat the Pirate King.
A master swordsman who aims to become the World's Strongest, surpassing Dracule Mihawk, Zoro is Luffy's right-hand man.
Luffy will only become the Pirate King if he gets his hands on the legendary treasure, and for that, he has to reach Laugh Tale.
Monkey D. Luffy has mastered all three types of haki, including Kenbunshoku Haki (Observation Haki), Busoshoku Haki (Armament Haki), and Haoshoku Haki (Conqueror's Haki). He can even use several subforms of the hakis, which makes him one of the most powerful haki users in the One Piece world.