I don't think there can really be a more dramatic result than a struggle so close that nobody can pull one over on an opponent.
Mark is and American. The only thing that matters in America is winning!
If you really want a winner, I would consider the player who took their turn last the loser. IMO It is easier for the last person to go all out and win than the first player.
Or you could have the player with the most points in the last round the winner.
Or you could play another round of the game to determine the winner.
If you have to have a winner, you will need to figure out a house rule. I would recommend out playing everyone else next time so it is not an issue.