What I think its alot more fun to think about is the next next member^
I also hope its some kind of fishman or mermaid. Because a person like that really could do alot of good things for the crew like many ppl have said, but what I really know wanan c is a Female new member that really will be some kick ass close combat person. Op clearly has to few female fighter overall and its not like many of them are any raw strengt person.
another thing that I wanna se in op is some kind of romance wich now seems to be pretty stuck ….a new female crew member would hopely mix that upp a little and she could be a little more forward and by there starting a chain reaction but thats probely just very much a dream^
So basicly you want a One Piece Sakura clon who can beat Luffy up harder than Nami does, and fall in love with him later on. xD j/k
A character like that would be cool, but needs to be done in an extremely original way or eveyone will be telling the resemblance with Naruto.