i think jimbei to me is the most likely person next to join the strawhats. this has probably been beaten with a bat already so it would be useless to argue over it now.
im also under the impression that luffy's crew will mirror that of blackbeard and currently blackbeard has 10 members (including bb) and 1 pet (stronger). luffy is 1 pet and 1 person short (currently) so i would also like a cool pet to join so i'd probably nominate the dragon for such role. this is just a hope tho.
also, oda, has made the mugiwara crew one that is pretty diverse but with the amount of diversity that exist in one piece i doubt we'll get 1 of each for the crew. with that said, i'd still like to see a logia/ex-marine. the closest to me who would fill this role are kuzan and smoker (yea everyone has mentioned them and want them to join too guess u could toss me into that group). i dont see them joining anytime soon though if they do. i also would like a situation where saul left the marines to happen to the person who joins luffy's crew :ninja:.
and finally, with all thats said above, the only person i see joining this saga is only jimbei, he just fits. apart from that i would love for enel to join and i probably will never complain or want for any other member to join luffy's crew ever again