GeForce Now is much more in tune with what I'm looking for when it comes from a streaming service. I buy the game on Steam / Epic / Ubisoft / Origin / Etc, and it's there to stream. Right now in the beta, there's not even a monthly fee yet. Even with a monthly fee, I'd rather have a service like that than one where I buy the game on a Google platform that I can only place when streaming from Google.
I was really hoping that Stadia would go a step further than GeForce Now and really work with the above companies to consolidate libraries just for streaming purposes, in the same way Movies Anywhere works for iTunes, Amazon Video, Etc. As it stands, GeForce Now is the far superior service for my needs.