Favors is the least sound shooter on the team (especially now that Gobert cleaned up his mechanics issues significantly) if you are looking at it from a mechanics perspective. More than anyone else on the team he will shoot on the way down, and it's not like he does it every time either. You can also see him aiming his shot more than anyone, resulting in varying release points.
Exum has a stiff shot motion, but he is mechanically sound most of the time. His issue comes more from comfort/confidence level taking jumpers and the whole having shoulder surgery thing.
This is backed up by FT%. Favors is the worst FT shooter on the team. Exum has been 80% his last two seasons played.