I think Santos. Right now Neymar father seems to want to make Santos work around Neymar so there is no reason to join a European team where he will just be a player and nothing more. Just with marketing in the brazilian market they can earn a lot more money. Even buy part of Santos to try to make it shine again.
The way Neymar is playing now, he will get hurt and do nothing for weeks if he goes to a serious team.
But I was very surprised to see that he almost joined Fluminense