Depending on the opponent, it would be Wilder. Since the foe is unknown I have to go with Ortiz and Ruiz. This is a bit of a crossroads fight for the two of them. Ortiz looked old and very slow in his recent win over Charles Martin. In fact, he was losing the fight on all scorecards when he nailed Martin in the sixth round. Ruiz' only fight since he lost the Joshua rematch two and a half years ago was a UD win over 40 year old Chris Arreola. This was a fight in which Ruiz was knocked down in the second round. If either of them have anything significant left this would be the fight to show it.
Three guys who would be beaten by any one of a dozen young lions who are not given a chance. Put Wilder against a good opponent, and have the winners of the two fights fight each other, the winner of that getting one last chance. Then cycle all of them out, or make it clear that from here on in they are only getting "opponent" money.