Which isn't saying much since the only good recent comparison was Sonic Frontiers, which I've heard was fine, but not great. Shadow Generations might be the last highly regarded 3D Sonic game since....well, Sonic Generations. In terms of all projects, probably the best received since Sonic Mania. Lost World, Boom: Rise of Lyric, Forces- the less said about those, the better.
I'm sure a Shadow show or film could be good, so long as Shadow isn't shoved to the side in his own project like Knuckles was in his show. And if it's not based on the actual awful Shadow the Hedgehog game.