I am also on PhotoLab and have been very happy with it, the killer features for me are the spot removal tool and the perpetual license model. Darktable would have been able to satisfy both of those features, but when I tried it years ago, I had to go back to the menu to select the tool for each spot I wanted to remove and it was just not workable. Darktable had many interface annoyances of this sort and I am not sure if it has improved since.