What approach should 3D Sonic take next?

Lost World in both forms are such strange games overall to me, and I'm still not sure how I would really rate them. I remember actually being really excited at the reveal of the Wii U version. The opening of Windy Hill with the different paths on all sides of the cylinder seemed like such a great idea. I instantly thought that each path would lead to another planetoid, each one with its' own further set of forks. I envisioned this enormous potential for later levels to have huge, intricate, uniquely shaped worlds packed full of crisscrossing, interchanging routes. Then I played the game and found each "side" always just led through the same linear sequence of planetoids, the recurring problems of "alternate routes" that are just shortcuts or different ways through the same general area.

The rest of the game is just a complete mixed bag of good and bad ideas in both 3D and 2D. Parkour was fun, the spindash with its' proto drop dash behavior was great, but then there's really poorly used Wisps and the watermelon festival. Cosmetically, the music is the only thing that stands out, and even then there are some clunkers. The worlds are incredibly generic. The Deadly Six are awful and very "un-Sonic" (although I actually did like Crack Bandicoot, or Zazz as the game calls him). The complaints Colors gets for being "like Mario" are much more appropriate for this game, just compare Sweet Mountain with Des(s)ert Ruins.

3DS Lost World starts out VERY strong. I was actually playing some of it yesterday, and was surprised at how good the first few stages are. Great level design, really pleasing movement with an improved parkour system, and an exciting sense of flow. More 3D Sonic like that would be excellent, but then of course the game decides to reenact the opening cutscene with its' own uncontrolled nosedive. I'm one of the least critical Sonic fans around, and even I can't defend the absolutely miserable Frozen Factory 3, and honestly I'd be a little afraid if I found myself in the same room with whoever designed it, as he's clearly severely unhinged.

 

I'm actually curious to see that list of yours, if you happen to actually have a record of it somewhere. I haven't played 3D Sonic games in a while now besides the storybook series, and I'd be interested to go back and take another look at other games. I know a point that gets made a lot is the fact that Sonic games are inconsistent, but there's surely some gems within each game that highlight the positives of this. I'm also kind of curious to hear by what sort of metrics you feel a Sonic level is good (though I assume these vary from game to game).