Lucci has no love for Luffy, and he is still attempting to have Nico Robin captured. His loyalty is to the World Government and the World Nobles, which means that there is no chance of him ever joining the Straw Hat Grand Fleet voluntarily.
11/12 Brook, The Musician
Also known as Soul King, Brook is the musician of the Straw Hat Pirates who joined them after the events of the Thriller Bark arc.
There are two characters, who have been heavily linked to becoming the next Straw Hat. These are - Carrot and Yamato.
Yamato needs Luffy's approval to join the crew and, once he gets it, he's officially going to be the 11th member of the Straw Hat Pirates.
5) Katakuri
As the man who is identified as the most probable captain of the Big Mom pirates, it's incredibly unlikely that Katakuri will join the Straw Hats barring his own crew's disbandment.
On the day of the Fire Festival, Zeus joined the Straw Hats on the Thousand Sunny as they entered the battle with the Beasts Pirates.
6/15 Won't Join: Enel Has A God Complex
The reason that he won't join the Grand Fleet is pretty simple and that is because of his God complex. He won't be willing to join Luffy, whom he considers to be inferior.
The cover page of chapter 861 depicts Nnekomamushi surrounded by 13 cats some with characteristics of the Strawhats. This led to the theory that nekomamushi embody's Thousand Sunny and the 13 cats are the total number of strawhat members by the end of the series.
Kid would eventually change his mind, but still acting as a reluctant ally for the most part, only joining forces with Luffy for the sake of their rivalry.
Yamato decided to stay back in Wano simply because Oden started his journey by going from region to region in Wano as well. Yamato still idolizes Oden and wants to follow in his footsteps. As such, he decided to explore Wano first and then set out to sea at a later time.
The alliance between Luffy and Law is officially over and law never betrayed him.
2) Zoro. Zoro's awakening of Advanced Conqueror's Haki solidified his place above the Straw Hat chef. Zoro has always been the second strongest member of the crew, a worthy title for the ship's vice-captain to hold.
Seeking help from the Straw Hat Pirates, Vivi ended up sailing with the crew all the way to Alabasta. Ultimately, she was faced with the choice to either join the crew or look after her country and do her duty as a princess. Vivi chose to stay behind, however, she remains to be an honorary Strawhat to this day.
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.
Well, Chopper is actually the youngest Straw Hat, and he is periodically treated as such. It is not unusual for Chopper to be babied by characters such as Robin and Zoro.
How old is Brook? Brook is by far the oldest member of the Straw Hat Pirates in One Piece. Technically speaking, this musician died when he was 38. However, he had a Devil Fruit that resurrected him.
2) Tony-Tony Chopper
Tony-Tony Chopper is the Straw Hat doctor, serving as only one of two people on the ship whose education can be classified into a specialty field.
Every single Straw Hat Pirate is without a doubt loyal to their captain, and they will undoubtedly offer their lives for him in a heartbeat. Of course, Luffy will definitely do the same. But like most things, there is one crewmember that stands above the rest in terms of loyalty to Luffy -- Roronoa Zoro.
The crew's first mate is Zoro, who is Luffy's right-hand man and the most powerful man right after the captain. Below Zoro rank two strong fighters: Sanji, who is presumably the third strongest Strawhat, and the former member of the Seven Warlords, Jinbe.
Baby 5. Although they initially fought against each other at Dressrosa, Baby 5 fell in love with Sai. After he dismissed her, she prepared to kill herself, but Sai stopped her and defeated Lao G after declaring that he would marry her regardless.
Listen, well, Enel lacks the admiral level stamina, armament haki (may have achieved it in the meantime), and overall physical strength.
There is a decent possibility that she will eventually join the Straw Hat Grand Fleet. She outright referenced Luffy in One Piece Chapter 1059, talking about how much she missed him. It's also possible that Hancock may join the Cross Guild instead, alongside former Warlords like Crocodile and Dracule Mihawk.