Google maps may or may not be good for road travel, I don't know. I don't drive. They certainly seem to suck for public transport planning because of silently added walking times that you can't turn off, and overcomplicated 3D-chess like UI, that's hard to navigate and automatically jumps around the map for no really discernible reason.
On a recent holiday, I had to constantly switch between gmaps and one other app with better actual mapping data/display (just because one has better public transport data, and the other is better at actually being a map - having things like a scale!, or contour lines).
A lot of walking/cycling tracks were just not there in gmaps at all, nevermind the washed out display style of the map tiles and lack of clearly visually defined features you typically orient yourself by when walking, like houses, or other important things you need when planning a walk, like contour lines. Or let alone a scale for quick orientation on how far something is at the current zoom level.
All they really have going for them at this point for me is public transport data (not the UI though).
A case in point:
Google "maps": https://megous.com/dl/tmp/46f0e2aff9573bba.png
Actual maps: https://megous.com/dl/tmp/003b6d5bc0f15199.png (with forests where forests really are, lol)
ADDED: Very nicely done. Just bought it.
As an example in 2019, we climbed on Mount Shiroyama above Kagoshima and looking at Google Maps the only way down to the city was the one we came from or some car only tunnels.On the other hand OSM listed a path with lots of stairs the locals apparently use to get up and down the mountain quickly.
If we used only Google Maps we would have to backtrack quite a bit over parts of the city we already went to but instead we arrived back in the city quickly just in time to get a tasty evening ramen. :)
Sure, that's reasonable, too. I think OSM (the project & database) wins in that situation, even if its derivations don't compete.
Again, I don't really see OSM directly competing with Google Maps (the app).