Sengoku: The Buddha
An admiral with control over three types of Haki, Sengoku is known as the most senior official in the Navy as the Fleet Admiral. He is one of the members of the old generation who challenged Whitebeard, Roger, and Shiki in their prime. As an admiral, he possesses all three types of Haki, and his devil fruit powers are extraordinary. He can transform into a Buddha, with all physical stats maxing out. A single punch broke the execution platform and sent the members of Blackbeard's crew flying. The shockwave from his blows deals severe damage. As the Fleet Admiral, he is a brilliant tactician and leads the world's navy members.
Sengoku from One Piece
Monkey D. Luffy: The Emperor of the Sea
The 19-year-old Emperor Of the Sea is the youngest on this list and has the highest potential and talent. He managed to defeat the world's strongest animal, Kaido, even though he needed some help along the way. With him awakening his devil fruit and being able to transform into Gear 5, it's only a matter of time until he fully masters it and increases its endurance. He has earned the respect and fear of the most powerful characters, such as Shanks and Kaido. With his battle experience and proficiency in Haki only increasing, Luffy is on his way to becoming one of the strongest pirates in One Piece's massive world.
Luffy from One Piece
Dracule Mihawk: The Strongest Swordsman
Known as the strongest swordsman, Mihawk is a lone wolf and manages to become a Warlord despite having no crew. Many journey far and wide to challenge him, including Zoro, and they've all lost. He doesn't have devil fruit powers, as his sword skills and Haki are more than enough to defend himself. With one slash of his huge cross-shaped sword, he managed to cut a huge iceberg in half and destroy a huge ship. With his incredible agility, observant eyes that gave him the nickname Hawk-eye, and mastery of Haki, he came to be known as Shanks' rival, who is an Emperor of the Sea.
Mihawk from One Piece
Sakazuki 'Akainu': The Lava Admiral
The current Fleet Admiral of the Navy, Sakazuki is as twisted as he is powerful. His devil fruit gave him the scary power of becoming lava. Although he was no match for an angry Whitebeard, he dealt serious damage to him and contributed to his death. His endurance is off the charts, as he battled Aokiji for ten days straight on Punk Hazard and came out on top. His body is extremely strong, withstanding two consecutive full power punches imbued with both Haki and devil fruit powers from Whitebeard and still getting up to fight.
Akainu from One Piece