I think Mbappe or Messi since their national teams could play longer than the others. For Neymar I think he will have many forwarders playing with him that will take a part from his goals.
CR7 I don't expect much from him and Portugal. I prefer to be wrong and see them playing good..
Neymar Jr will play with his fellow brazilian stars, and they would do what's they are best known which is goals and amazing skills we don't know exists. France, I don't think they would be able to break the cause that have befallen the previous defending champions of world cup. The past champions don't always qualify from the group stage which is very poor and have taken big measures in the world cup. It's also known as world cup cause and I'm fully hoping that France breaks it this time around. Messi and Ronaldo, I think it's the end of era of the both G.O.A.T.S this might possibly be the last time we would witnessed high class football game from both of them, so I'm definitely going to use my time to enjoy their game.