I haven't played that many Sonic games, so I'll first say that Sonic Rivals 2 is my favorite game I've watched. I liked the casual story, Shadow's portrayal, the music, the levels' aesthetics, and how Professor Gerald got mentioned.
But of the ones I've actually played myself, I guess I'll have to say Sonic Forces for the pretty graphics, music, and the custom avatar feature.
But of the ones I've actually played myself, I guess I'll have to say Sonic Forces for the pretty graphics, music, and the custom avatar feature.