I think the Shichibukai group in general in one of the best one Oda created in the manga or at least the original ones.
Mihawk - first Shichibukai to show the real danger of grandline by humiliating Zoro, ending up as his ultimate goal, with his loner attitude while seeking for the strongest swordsmen, his rivalry with Shanks alongside an awesome design
Crocodile - defeated the main multiple times, showed a great threat lvl in alabasta, grandline experience, ambition seeking pluton(one of the ancient weapons) , while having a great swag
Doflamingo - his trickery, usual laugh / smile, original design with the pink swag in contrast to Crocodiles, past as celestial dragon while becoming a commoner allowing him to experience the life style of both sides, cruel attitude ending up killing his father, his brother, while being the first major antagonist of the new world in development with a previous crewmember(Law) seeking to avenge his brother
Kuma - A revolutionary disguised as a pirate tyrant in a secret mission only known by Dragon before the events of MF, becoming a Shichibukai, working for the government undercover with mysteries surrounding the reason behind experiments on him to create pacistas, ultimately becoming one himself and being treated as a slave by celestial dragons. All that while being singlehandily responsible in giving a crushing defeat to the SHs twice while saving them at the same in preparation to the 2 years time skip
Hancock - A former slave saved by Fisher tiger from celestial dragons, growing alongside her sisters after eating a fruit, becoming the princess of Amazon lily, conquering the world with her powers, her beauty, except for the one she actually fell in love with(Luffy) lol, ultimately playing the role of ally
Jinbei - representation of the Fishman race, knight of the sea, who originally seemed to have superiority complex through Arlong's doings until hearing their story, the story of Fisher Tiger former slave of celestial dragons, trying to follow into Fisher tiger's path and acting as a symbolism between humans and fishmen, great bond with Ace which indirectly created another one with Luffy, ultimately saving his life by sharing blood with him in FI and ending up as a crewmember to look over him as Ace wished as well as helping him accomplish his goal
Moria - Initially viewed as a super rookie until losing to Kaido in Wano, experiencing the pain of losing his men without being able to do anything, basically an alternate version of the Strawhats if they didn't have plot armor, all of that pushing him to change his motto into a "lazy" motto, counting on zombies to do his bidings
So overall the stories behind the original Shichibukai, their impact into the story was awesome, so much that i can't even tell I dislike any of them, but if I were to rank them from favorite to least favorite, it'd probably look this way
1. Mihawk
2. Kuma
3. Crocodile
4. Doflamingo
5. Boa
6. Jinbei
7. Moria
If Law, Teach, Buggy and Weevil are counted, it'd look more like this though
1. Law
2. Mihawk
3. Kuma
4. Crocodile
5. Doflamingo
6. Boa
7. Teach
8. Buggy
9. Jinbei
10. Moria
11. Weevil
Mihawk - first Shichibukai to show the real danger of grandline by humiliating Zoro, ending up as his ultimate goal, with his loner attitude while seeking for the strongest swordsmen, his rivalry with Shanks alongside an awesome design
Crocodile - defeated the main multiple times, showed a great threat lvl in alabasta, grandline experience, ambition seeking pluton(one of the ancient weapons) , while having a great swag
Doflamingo - his trickery, usual laugh / smile, original design with the pink swag in contrast to Crocodiles, past as celestial dragon while becoming a commoner allowing him to experience the life style of both sides, cruel attitude ending up killing his father, his brother, while being the first major antagonist of the new world in development with a previous crewmember(Law) seeking to avenge his brother
Kuma - A revolutionary disguised as a pirate tyrant in a secret mission only known by Dragon before the events of MF, becoming a Shichibukai, working for the government undercover with mysteries surrounding the reason behind experiments on him to create pacistas, ultimately becoming one himself and being treated as a slave by celestial dragons. All that while being singlehandily responsible in giving a crushing defeat to the SHs twice while saving them at the same in preparation to the 2 years time skip
Hancock - A former slave saved by Fisher tiger from celestial dragons, growing alongside her sisters after eating a fruit, becoming the princess of Amazon lily, conquering the world with her powers, her beauty, except for the one she actually fell in love with(Luffy) lol, ultimately playing the role of ally
Jinbei - representation of the Fishman race, knight of the sea, who originally seemed to have superiority complex through Arlong's doings until hearing their story, the story of Fisher Tiger former slave of celestial dragons, trying to follow into Fisher tiger's path and acting as a symbolism between humans and fishmen, great bond with Ace which indirectly created another one with Luffy, ultimately saving his life by sharing blood with him in FI and ending up as a crewmember to look over him as Ace wished as well as helping him accomplish his goal
Moria - Initially viewed as a super rookie until losing to Kaido in Wano, experiencing the pain of losing his men without being able to do anything, basically an alternate version of the Strawhats if they didn't have plot armor, all of that pushing him to change his motto into a "lazy" motto, counting on zombies to do his bidings
So overall the stories behind the original Shichibukai, their impact into the story was awesome, so much that i can't even tell I dislike any of them, but if I were to rank them from favorite to least favorite, it'd probably look this way
1. Mihawk
2. Kuma
3. Crocodile
4. Doflamingo
5. Boa
6. Jinbei
7. Moria
If Law, Teach, Buggy and Weevil are counted, it'd look more like this though
1. Law
2. Mihawk
3. Kuma
4. Crocodile
5. Doflamingo
6. Boa
7. Teach
8. Buggy
9. Jinbei
10. Moria
11. Weevil