Both John Loftus had Jeff Lowder have repeatedly challenged W. L. Craig to a public debate. Since they're both competing for his attention, perhaps they need to begin with an elimination round. The survivor can proceed to the next round.
There are many potentially interesting match-ups. Problem is, there's only one Craig and many aspirants. He can't debate them all. He can only debate a small fraction. And he's already 66, so the opportunities are rapidly diminishing. He has to be very finicky.
In fact, I expect some aspirants are getting desperate because they know time is running out.
He debates people who are either highly credentialed or very prominent. There's also a difference between who you debate when you are getting established, and who you debate after you are established. Once you have a reputation, you attract bigger fish.