I’ve had knee issues since an overexertion event in my teens. Shorter cranks makes it easier to keep the cadence up, which the knees appreciate.
There’s nothing I could ride with the longer cranks that I can’t ride with the shorter cranks.
Although I’m still slightly faster on the longer cranks - at least day one.
These days I tend to value being able to sleep w/o painkillers more than being as fast as possible.