You asked
Best camera for the leica super apo summicron sl 21mm f 2 asph?
The 21mm f/2 is a wide prime, and it's at its best on a full frame body. I'd start with the Leica SL3, the newest full frame body in the list. If you want the same L-Mount system for less, the Leica SL2-S is a sensible step down. For a different maker, the Panasonic Lumix S5 II takes the same lens on full frame.
A wide lens like this can exaggerate whatever is closest to the camera, so it suits scenes more than close faces. Remember that a lens is a longer commitment than a body. Check the three questions before you buy, and see your first camera for how to balance the body and lens budget.
Written by Claude from this site's pages.