Why wouldn't Jason lose? Forgive me, since I know very little about him besides that he's hard to kill and he's got a fuckhuge machete. It just seems like Predator has an edge in everything else
Also, I picked Aile because like Ben, she can assume a variety of forms, though apparently not as powerful as Ben. But they're not chosen at random
As for Khan, he's shaken off similar injuries, plus has thousands of years worth of experience and souls he's stolen to add to his strength.