Imu is the sovereign of the World Government and arguably the strongest character in One Piece. Imu seems to have access to some kind of ability/weapon that allowed him to destroy the Kingdom of Lulusia in an instant.
As such, Luffy awakened the true abilities of the Nika fruit. With its powers, Luffy was able to topple even Kaido and if he could defeat the man who was the Strongest Creature Alive, he can certainly defeat Shanks as well.
Against Shanks, even if Luffy possesses weaker Haki, the Devil Fruit abilities of the Hito Hito no Mi, Model: Nika can make up for the deficit and see him emerge victorious. Currently, however, Shanks is likely stronger than Luffy, simply due to the fact that the plot demands that of him.
1) Blackbeard
While many theorize that Luffy's Awakening will be specifically tailored to defeating Blackbeard, this has yet to happen in One Piece and thus is still speculative. Even with Advanced Conqueror's Haki, it's likely Luffy doesn't yet have the tools needed to defeat Blackbeard in a fight.
1 Monkey D. Luffy, The Captain
Luffy is the by far the strongest member of the Straw Hat Pirates. As the Fifth Emperor of the Sea, Luffy is incredibly powerful and is able to hold his own against the Yonko of the One Piece world. He uses the power of the Gomu Gomu no Mi in incredible ways and keeps getting stronger.
Four members of the crew possess Devil Fruit abilities: Luffy, Chopper, Robin, and Brook. Luffy has awakened his fruit and has used its alteration of his body in a massive variety of creative ways to adopt new forms which increase his power and fighting capabilities.
Nami. Nami may be the weakest crew member, when it comes to strength, but she is far from useless. Her navigation, weather prediction, and cat burglary skills are unmatched. Nami knows she is nowhere near as strong as the other crew members but that doesn't keep her out of a fight.
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.
Updated December 19, 2021 by Rei Penber: The Pirate King, Gol D. Roger, is quite easily one of the strongest pirates in the story, and other than Whitebeard, no one can truly be considered an equal to him. Yet with time, more characters who wield tremendous strength themselves have been introduced in the story.
Chapter 1058 of One Piece answers the question definitively when Mihawk's bounty is revealed. It is stated explicitly that Mihawk's skill as a swordsman surpasses Shanks' abilities. Because of his exceptional power and skill within the world of One Piece, Mihawk is given an incredible bounty of 3.59 billion berries.
1 Gol D.
Roger was incredibly powerful and the only known person to have ever matched him in combat was none other than Whitebeard himself. In terms of strength, Roger was a true equal to Whitebeard and his biggest rival ever.
Blackbeard is the greatest pirate rival of Luffy. He'll certainly be the final obstacle of Luffy.
It depends on how quick the fight will last. Luffy's Gears are costly and can't be maintained for long stretches of time and neither can Baryon Mode for Naruto. Due to the number of drawbacks the Baryon Mode brings, Luffy will probably clinch victory in Naruto vs. Luffy if they break those modes out.
Is Luffy Gear 5 the strongest? Yes! Of course, Luffy's Gear 5 is the peak of his colossal powers. He can literally do ANYTHING with his devil fruit powers right now, as he transforms into the Sun God Nika when using Gear 5, making his devil fruit the strongest in existence so far.
Edward England is known today as one of the more humane pirate captains of the Golden Age of Piracy.