The problem I've seen with these stories is that it never feels like anything's at stake. Sure, the characters are well written, but the stories simply aren't adding anything to the game. The stories in games like Adventure may have been melodramatic and stupid, but at least they mattered. That's something I miss. That said, there's no reason why a larger-scale more epic plot can't be fused with goofy childish characters.
Sonic stories have always struggled with high drama - SA2 and 06 prove that several times over. I'm actually a lot happier with the plot from Colours/Generations/Lost World than I have been with the ones before that. That said, SA1 wasn't bad.
So dang melancholy yet happy. Gamma's storyline was amazing. On further reflection, honestly I have to say I think some of the best storytelling in a Sonic game is actually on Lake's BTS/ATS. Those cutscenes have legitimate funny moments, legitimately cool moments, and most importantly, each one forwards the plot in some way, shape or form. Definitely telling of the sheer talent of Lake and Lange, but also proving good storytelling is possible for Sonic games.
The only Sonic game that has attempted a decent narrative has been Sonic Battle. Everything else has been total dreck. I see some people praise the Colors-style games for their approach but they do it horribly too. Sonic is lame, Tails is superlame, everyone else is baggage or the butt of a banal joke, no one can fucking voice act worth a darn except for Pollock. People really only stomach this crap since they don't have much to compare it with in-series. Looking at something like the Ratchet and Clank series though, the difference is night and day.
E-102's storyline was just perfect. I'm almost convinced the whole thing was an accident of good writing that just happened to end up in a Sonic game. I'd say everything else 'afterwards', as I always praise SA1's narrative to an extent (see above) Other than that, I do concur. Sonic Battle was the last time I remember a Sonic game actually using it's wider cast of characters in a way that felt like it made sense to the game's plot. No-one felt overly shoehorned in (except maybe Chaos 0, but glorified cameos are another thing entirely), and each character actually bounced off eachother to create some decent and amusing dialogue. Hell. They even captured both sides of Knuckles (The 'Emerald Guardian' side of his older games, and the 'Comic Doofus' side he's shown as now) in a way that didn't feel too awkward.
It's not a complicated one to write in that a robot built as a war machine gains free though and realizes it and its brothers are slaves. Then it sets out to liberate them. Add the twist that all of the robots are fellow birds, and the main rival happens to be your best friend, and it's a very simple but effective plot. People would be rather surprised how well simplistic little plots can play out in something like a platformer. Grand scale DARK STORIES and GOVERNMENT CONSPIRACIES are all just needless twaddle. The series never benefited from it and it only needlessly divided the fanbase, especially once the series launched on Gamecube. I'd say leave more complex stories to stuff like RPGs. Platformers don't need it. In fact, I firmly believe that a lot of the problems the series suffered came from the new audience SA2B brought in on Gamecube. People got the wrong impression on what Sonic is or is supposed to be, and Colors and Generations have slowly restored things to a state of what it should be. Lost World seemed to try a bit hard to pander to the Nintendo side of things again since it feels like the most Nintendo Sonic game of the whole lineup.
