Google Maps has better navigation, but Comaps and OM have better management of bookmarking places. The search on Comaps often suffers, so I mainly use my bookmark list searches for stuff. I haven't used OSand because it was so clunky and horrible right off the bat, but supposedly that is a way to access OSM bus routing. Considering how unreliable many municipal transit network apps and their Google Maps integrations are already, that's just to be expected tho. Huge benefit is being able to more easily export that data for use in Emacs Orgmode, as with other log files, but that's kinda complicated

Google Maps has an insane amount of resources & the time economy of FOSS devs is totally managed by nonprofit donors and/or also overlapping with larger tech employers