Lots of us probably prefer Google Maps over Apple Maps on our iOS devices.
Considering the only input method for maps on the Apple Watch will be Siri, which doesn't (currently) natively support 3rd party apps (although they can have their own dictation functionality), if you just want to lift your wrist and dictate some directions, you'll be using Apple Maps (just like Siri on iOS), even if Google release Google Maps for Apple Watch.
So, for those of us embedded with Google, we're going to have to learn to love Apple Maps.
I'd suggest using Apple Maps on your phone so you can start submitting corrections.
To be fair, Apple Maps has come a long way - at least where I live. I still prefer Google Maps for points of interest but I'm able to use Apple Maps without much of a problem these days.