The Samyang 14/2.8 is good value for money.
Sharp all the way to the edges.
The trade off is the distortion, but that is correctable to a point and often not obvious.
K1+Samyang 14/2.8
M20/4 is small and nice.
Not the sharpest on the edges, but certainly enough.
Corners are weak, but they either get cropped off anyway after distortion correction or don't contribute the a photo to be of bother.
K1+M20/4
K24/2.8 properly adjusted for the edges to be at/near infinity is actually very nice.
Small, fast and a pop to the images if used in the f3.5-f4 region.
K1+K24/2.8