the problem is that some people here think that their candidates will join, just because they found something in common between their candidate and a SH member, even though that thing is unrelated to joining matters, and they tend to force these things for their candidates, which makes their explanation really stupid.
for example if Luffy told Zoro to help him, and said the same thing to their candidate, then they will say that their candidate must be joining, just because Luffy told him/her to help him, just like Zoro.
for me, what really matters is what the characters themselves say and want, what they have in common with SHs, and these common things should be related to joining matters, to SHs matters, not just some random things, that's why I think Yamato will join, because she wants to join, she said that she will join, she knows Luffy's dream just like the other SHs, and when Momonosuke called the SHs with their joining order in chapter 1056, he called her after Jinbe, which was a clear hint since Momo doesn't know the SHs joining order (Luffy, Zoro, Nami, Usopp, Sanji, Chopper, Robin, Franky, Brook, Jinbe, Yamato, that's what Momo said.)
so no matter how many times you try to deceive yourselves, it's clear that Yamato has highest possibility of joining, because she has a lot more things to be a SH than any other candidate.