Search engine wise they are clearly on top. On the other hand, do enough social engineering and people will start using a worse product regardless.
Youtube could of course force ads on its users, but that would also make those users less interested in youtube compared to competing platforms.
This is not overly simple.
Who do you think click on ads, you or her ?
Apple map ? Outside of the US, not even close.
Google search, just forget about it.
Traffic is accurate, although it is be a little slower to update than Google Maps (it seems to be ~5 mins behind). Directions are spot on and the UI (at least in CarPlay) is clear and detailed. The only thing that's poor compared to Google Maps is the search but it's certainly a decent alternative and it's come a long way since it was first released.
I'm in the UK I use both Apple maps, Google maps, OpenStreetMap and Bing maps regularly (in addition to the built in nav system in my car) and for me the only noticeable strength that Google has is streetview. The "satellite" view in Google Maps where I live is actually so old (12+ years) that it's actually becoming useful for researching historical stuff...
I can speculate that outside of Europe its even worse.