I donk lead with a pretty polarized range of really strong hands/draws or more airish type hands. If I'm donking with air I like to do it on boards that have obvious draws, that I can continue repping if they hit on turn or river.

Boards with flush draws are good to donk lead with a FD as well as air, as ppl will often put you on the FD once you donk, so they'll give your bet a lot of respect if the flush comes in on any street. Its also good to do this with a FD/air cause you don't mind getting raised in either of these spots. Air you can just fold, and FD you can jam over sometimes.