Rawtherapee seems sharper to me to.
Here is a comparison, using the raw from this thread:
20200718_0062-dt_01.CR2.xmp (40.8 KB)
darktable 3.4
20200718_0062-rt.CR2.pp3 (11.3 KB)
rawtherapee 5.8
In both versions I have disabled everything except white balance (as shot in camera), and crop, so you can view 100% on screen. Both used Amaze demosaic. Both used linear pro photo as working space. Both saved to jpg, 100% quality, no resize.
Rawtherapee is a little sharper, though the difference is quite subtle. Is this simply due to different implementation of Amaze algorithm?