Batman vs. Black Panther
An entire year of prep for both of them. They have all of their normal resources to bring to bear in their prep and they know the other character as well as that other character's best friend knows them. So BP knows everything that Superman knows about Bats and Bats knows everything Cap knows about BP. They fight in a neutral city and the only tools they can bring with them, they have to carry in. Who wins between the kings of prep-time?