It's tough to choose a single favorite game, there are quite a few that I would consider my favorites. If I had to choose though, I'd probably have to say Bayonetta, Skyrim, and Dark Souls 3 are some of my favorite games of all time.
As for the best game I've ever played, without a doubt it's Bloodborne. I love that game so much, it's inspired me a lot and made me realize the artistry within video games. Kingdom Hearts 3 is probably a close second.