In the spirit of Kool Keith, right now there are a lot of under-the-radar fringe rappers cranking out dozens of projects. Who are your favorites, currently, or in the past? I'll add a couple I always check for. Not every experiment is successful, but I can always count on something interesting. I'd list Moka Only, but compared to the others I'm listing, his content might as well be Top 40.

Ten-headed Skeleton (Michael Nhat)
https://tenheadedskeleton.bandcamp.com/

Grape God
https://grapegod.bandcamp.com/music
https://timetravel444.com/music

Beans (did you know he's released like a half dozen albums in the last year or two?)
https://beansiswack.bandcamp.com/

Coin Locker Kid
2/3 of what he does is unlistenable, the other third is fantastic and makes me think he needs to be cast in some Hamilton-type theatrical rap project:

https://coinlockerkid.bandcamp.com/

Add on! Or else I'll just have to keep going.