I think Sonic all together has never been as good as people praise it, from the first game. Don't get me wrong, I love the original Genesis games, and I happen to own a Mega Drive which I used to play the games on a lot, but I've always found that Sonic's famous speed is what ruins the gameplay. The original games contain a lot of platforming, and it never feels satisfying because the controls are meant to work in a way that he quickly gains speed, making much of the difficulty of the game exist purely because of feeling unstable. I'd much rather play Mario Bros. with tight controls that move like you want them to. And modern Sonic still has that. Your always jumping too far and fast then you want to, and it just gets irritating. I'm not a huge fan of 3D Sonic but that is what really makes Colours and Generations stand out.
Unleashed day stages were pretty good too, but if you were to play the game without the Werehog stages, doesn't that still mean that is forces you to watch the shitty cutscenes and do the fucking atrocious town stuff?