One Piece is broadly divided into two periods: pre-time-skip and post-time-skip. Both periods are equally important to the story, so it is impossible to enjoy the series without either part. The period before the time-skip is focused on Luffy taking his first steps toward his dream of becoming the Pirate King.
Luffy recruited most of his crew members before the time-skip. This period featured some of the most powerful characters in One Piece, and they gained a lot of fans due to their strength and personality. Unfortunately, many of the characters have suffered a drop ever since the series entered the post-time-skip period.
7 Smoker
Currently, Smoker holds the position of a Navy Vice-Admiral, which is rather impressive, yet, he has been one of the more underwhelming characters in the post-time-skip period. Smoker has barely been involved in any of the fights and his last notable appearance came during the Punk Hazard arc.
Before the time-skip occurred, Smoker came off as an interesting character and an incredible villain, who was continuously chasing Luffy. He defeated Luffy easily at Loguetown and the pirate had to be rescued by his father, Monkey D. Dragon. With One Piece entering the final saga, the fans will be hoping that Smoker plays an important role.
6 Aokiji
No one expected Aokiji to leave the Marines and then join the Blackbeard Pirates, which is one of the most infamous pirate crews in the world. Aokiji left the Marines after losing the fight against Akainu. Aokiji made one appearance at Punk Hazard, where he rescued Smoker from the clutches of Doflamingo.
Aokiji was the first Admiral to be introduced in the series, and he taught the Straw Hats a valuable lesson that there are plenty of characters who are much stronger. He was also involved in the Summit War, where he rescued thousands of Marines with the help of his Hie Hie no Mi.
5 Gekko Moria
When he was first introduced in the series, Gekko Moria came off as a malicious character. Moria and his crew lived on Thriller Bark. Thriller Bark is a huge ship, which gave off a very creepy aura. In addition to the eerie ship, Moria's devil fruit powers allowed him to create zombies. The Straw Hats faced a lot of problems in the fight, and they had to rely on Luffy to pull off a miracle.
Moria's downfall began during the Summit War when Doflamingo injured him. Moria had to run away to keep himself safe from any harm. When he went to find Absalom, he was surprised to find his comrade dead and his fruit stolen by Shiryu. Moria was given an ultimatum by Blackbeard, but it is unknown whether Moria accepted or rejected the Yonko's offer.
4 Rob Lucci
When he made his debut in the Water 7 arc, Lucci cemented his place as one of the most ruthless characters in the series. He has no qualms about killing innocent people if they stood in his way. Lucci's dark history made his character even more impressive.
After recovering from his injuries, Rob Lucci joined CP0, an organization that is renowned throughout the world for its notoriety. Lucci has made a few appearances since the time-skip, but most of them have been very short, and he doesn't give off the same evil aura that he used to before the time-skip. He seems to have no will of his own as he just carries out missions on behalf of the World Government.
3 Franky
During the two-year time-skip, Franky improved his strength, and he learned a lot about science. Ever since the Straw Hats entered the New World, Franky has been involved in two great fights. One against Senor Pink and the other against Sasaki. Franky had to struggle quite a lot in both the fights, but he managed to come out on top.
Many fans have expressed disappointment over Franky's new design. Previously, Franky had a simple yet funny design, but with the new modifications, he seems like a completely different character.
2 Basil Hawkins
Basil Hawkins is the captain of the Hawkins Pirates, and one of the members of the Worst Generation. When Hawkins fought against Kizaru at Sabaody Archipelago, it seemed that he would go on to become an extremely powerful character, especially with his ability to have multiple lives.
Unfortunately, things went downhill for Hawkins after the time-skip. He was forced to join Kaido's crew and then in the Wano Country arc, Hawkins was defeated by Killer, and he failed to capture Luffy and Zoro.
1 Scratchmen Apoo
Until the Wano Country arc, Apoo's powers were a mystery to the fans. He was able to attack Kizaru at Sabaody with his devil fruit ability, but he couldn't injure the Admiral. Regardless of his inability to hurt the Navy Admiral, Apoo appeared to be a very interesting character.
Before the time-skip, Apoo at least had a sense of individuality, and he looked like one of the more promising Supernovas, but all of that changed. The fans had high expectations from Apoo and when it was revealed that he had given up his independence to join Kaido's group, it was very disappointing.