Keep in mind, among the worst sailplanes are 20:1 or higher.
Best jets.....I have no clue, guess high single numbers?
What about a current fighter jet?!?!

Here is a nice discussion from AOPA (I am a glider pilot with some power time, but mostly joined for the lobbyist's for GA and the CFI-G insurance), but this just popped up on a newsletter....

https://pilot-protection-services.ao...t-650-part-two