It is yes arguably a better service in most ways and better integrated with both game studios, a TV console, and all the benefits of Xbox live community. Nut Nvidia's is arguably a closer direct competition to Stadia.

Being a purely PC game (slash arcade) platform. As much as Xbox is trying to evolve and games being cross-console/PC is getting far more common the Xbox cloud platform is still largely just an extension of Xbox games.

For ex: with Divinity and Pathfiner: WOTR they all had to release "Enhanced Editions" to support Xbox and it takes many years after the PC release to get a lot of PC games. It's not one-to-one.

That said I see Xbox Cloud completely dominating this space. Their library, pricing, and service quality is A+

It would depend on the games you play. For example Stadia got games like Assassin's Creed and Cyberpunk 2077 that Xbox Game Pass still doesn't. Their streaming service is still limited to Game Pass games only.

It is actually line $35/year (for GP Ultimate) if you know magic words “conversion deal”.