The only reason I don't see a straw hat eating it is because of Ace's legacy. By that I mean that his fruit is a big deal, as evidenced by this tournament. Whoever eats that fruit is going to be in the newspaper and be known to everyone around the world. I don't see anyone in the strawhats, besides Zoro and that's not going to happen, get that much of exposure other than Luffy.
The only people in my mind who would eat the fruit are one of the Supernovas (won't be this option because they all have fruits except for Zoro and Killer), a high ranking member of a Yonkou's crew (maybe somebody in Shank's crew), a new Warlord, Sabo (lol), a high ranking member of the revolutionaries, or a high ranking officer of the navy.
Imo, it wouldn't really make sense for Luffy to carry the fruit along. It wouldn't be convenient for them. Someone would constantly have to stay on the Sunny to guard it, everyone would know they have it and would be trying to take it. The only thing they could do is give it to Raleigh to guard it, and unless he's going swimming all the way to the New World that is not going to happen.
The only other option is for the blind guy, as the new Admiral, to take it back to marine HQ.
Despite all that, the easiest thing to do with the fruit would be to just give it to Sanji. He's basically begging to eat it. He can light his own cigarette, he can basically cook anywhere, he can easily incorporate it to his techniques, and it would be interesting to see how he struggles to learn how to use the fruit. Some people would also argue that he needs something to keep up with Luffy and Zoro and with Franky creeping up from behind. Sounds crazy I know but I have heard people say that. I think the most interesting thing that would come from Sanji eating it is the moment when Luffy actually gives the fruit to Sanji. That scene would be very powerful. Luffy would be acknowledging his trust and would show how far their relationship has come.
What I'm trying to say is, I have no idea what Oda is going to do lol