Who would you like to join the Straw Hats?

Personally, I'd like no one else to join. I think 10 members is enough, and especially with Jimbei joining, their crew is already monstrously powerful. Sticking to what Luffy said earlier in the series about the size he wants, it would make a lot of sense to keep it at this size, and the relatively small crew is part of what makes them interesting.

But given that, I think any new addition to the crew could be made demonstrably separate from the rest by simply being a Logia user. I actually hope it's not the Mera Mera no Mi, mainly because I'd rather see something different, something that's not overtly powerful. Each of the Devil Fruits on the crew is intriguing in that respect, and I don't think that's something they should disrupt.

I think ten member are a lot to keep up with in a manga and adding any more would make the story unstable or difficult to keep track of characters and there development.

I am pretty certain jimbei is joining since its been pretty much confirmed by him.
If somebody new were to join in this arc I think it would be Wicca. Apparently there is a rumor that oda has said there would be a new female member (not sure if that's true but another female would make sense seeing how there are a ton of dudes). Also the other girls in this arc there character designs aren't very creative. Violet looks too much like robin and Rebecca looks kinda like nami and has something going on with that toy. For a character too join their design will have to be unique and different from the others. Wicca fits that for the girls. Also Wicca is strong and can be a spy or zoros compass.
I don't think kinemon will join since he has a son and the ocean/pirate life is not something for a little kid. Also I am pretty sure his samurai code prevents him from being a pirate.
Also if somebody new were to join I think that would be they would be the last to join. Because if they were to join that would make 11 (I count jimbei) and any more than that is too much.

I would love if Jinbie join I mean he's a fishman for Christ sake and he's strong. but I think the reason Oda didn't let him join is due to his bounty size first of Luffy is the captain and the captain should have the largest bounty and if we would call a Vice captain we all know Zorro would fit that role so we would need for Zorro to have a higher bounty then Jinbi and tbh I think Zorro is more stronger then Jinbi he just has that over powering bad ass felling. Sanji may or may not need to have a higher bounty then Jinbi but at leats close if not higher and if jinbi is stronger then sanji then it will ruining the already label nick name of the inhuman monster trio but I'm not sure if that's to bad. Another reason why Jinbi would do good in the straw hats is look at it this way each straw hat crew has clame to be the best at what they do zorro on the road of becoming the best swordsmen, Luffy the pirate king, Nami the best navigator, Ussop the best sniper(not sure if he is tho his dad may be lol), Sanji the best cock, Roban well the best and only person who can decipher the ponygliphis and read ancient stuff, Brook the best musician proven when he became big as Soul king, Franky the best shipwright/ (I think inventor almost loll) Chopper the best doctor, and now the strongest fish man and best in fish man karate Jinibi and the fact that most of the straw hats or different in many ways. he'll fit perfectly

I think no person we don't know already will join the staw hat crew. The only person I can think of are Jimbei or vivi. (They have shown vivi twice in a pretty short period of time so I think she might come back :S)
Why do I think no new person like Rebecca or anyone else will join?
Well this is because I think in the new world luffy won't be getting new crew members but will be creating a massive alliance.
Crews who would most likely join the Alliance:

Currently in the alliance
- Law
- Straw hat

Crew's or army's who I think will join:
- The army of chinjao ( After luffy restored his head he said his sons army was under luffy's command.)
- Bartelomeo ( He loves luffy :D )
- Boahancock (Kuja pirates) (Hancock said they would help him whenever they needed)

Crew's or army's that might join:
- Old whitebeard pirates (captain marco)
- Vivi with arabasta army
- very little chance but maybe his dad will also help since it will be a fight vs the world.

He will need the big alliance to fight the world goverment in the end. It will probably be a big fight like at marinefort.
Also like many people say he already has every kind of member he needs in the crew.

And just adding random members would kinda ruïn the idea of the crew.
So I think oda will be creating a big alliance for luffy in the new world :D

This would also give some logic to the words white beard said. "you of the world goverment all fear the battle that will involve the whole world" . Massive straw hat alliance vs the world goverment.

Tell me if you agree or disagree or want to add any changes in my theory.

I would love Rebecca to join because the crew needs a female character, her backstory has already been revealed but I think there's more to it, I'm sorry I'm only keeping up with the anime and not the manga, and obviously the anime is different and I did read a few chapters of the manga and it was different, the reasons I would love for Rebecca to join is because, every character who joins, meets Luffy first, like zoro, nami, usopp and every straw hat. People are still saying she won't because she will claim back dressrosa? No she won't. She's not a vivi. ( I love vivi and would love her to join though ) anyways, she currently has the same goal as the strawhats, and if the anime will be very different from the manga and sabo won't appear, she's my next candidate and really what damage could a new female member do? Oda follows a pattern? Excuse me who expected robin to join? It was a very rare case and hopefully rebecca is, plus luffy wasn't against her when she said she wanted the mera mera no mi. And the strawhats could do with a logia, plus it's been shown that rebecca doesn't hurt anyone and she's a gladiator so she depends on her weapon. I'm sorry if I didn't clear my point or I didn't give enough reasons but I would really love her to join, and if violet would join too, that'd be awesome, plus violet is a possible choice since she's been working under doffy against her will. I hope they would soon release the English subtitle of episode 655 of one piece, can't wait!

Boa Hancock or maybe bartemeo

YES YES YES!!! A million times yes! I could be a fighter or Oh, I know, an apprentice to Chopper! Every pirate crew needs helping hands when it comes to injuries!
I made several characters but this one is by far the best.
The name of this character is Jura Evangelion, and she is the young apperntice to Chopper, since being raised in the jungle she has a medical journal's worth of herbal and bodily functions that can help the crew whenever she can, like Chopper, Jura has a zoan devil fruit called the Dino-Dino fruit model raptor, allowing her to transform into a raptor or human raptor hybrid.