Ahh… the best Sonic game in the whole franchise: Sonic Adventure 2. Even though Sonic DX is right up there with it, nothing tops it. From the soundtrack, to the characters, to the story, Sonic Adventure 2 trumps all.
1. The characters
I couldn't ever beat the whole Sonic DX game because of Big the Cat. Let's talk about how his whole story is based on fishing. I can't fish. I'm a fighter not a fisher. In Sonic Adventure 2, all gameplay is actually fighting oriented, with different fighting techniques and objectives. For instance, there's Knuckles and Rouge, who are the treasure hunters; Sonic and Shadow, the standard fighters; Tails and Eggman, the shooters. (Shadow isn't even featured in Sonic DX!)
2. The soundtrack
Sonic Adventure 2 is notorious for its soundtrack. Maybe it's because I used to dance around my room singing Amy’s and Rouge’s theme songs, but I actually know the songs in the game. In Sonic DX, I would know the songs if I heard them, but I can't name them off the top of my head. However: "Pumpkin Hill," "City Escape," and "Live and Learn" - these should all ring a bell and bring the nostalgia back. I've talked to at least three nerds, all of whom knew what "City Escape" was. That's the only evidence needed. Knowing the music by heart makes the game more playable, and all the lyrics are associated with the story, which leads me to the next point.
3. The story itself
There is a Hero story and a Dark story. The heroes include Sonic, Tails, and Knuckles, and the villains are Shadow, Eggman, and Rouge. The story is focused on these rivals and how they come together. The ultimate objectives are for Sonic to beat Eggman and Shadow to beat the Biolizard. Separating the characters’ stories is a lot harder because you have to master many specific skill sets. The story is also more enjoyable since the heroes and villains are united as teams.
I would've compared this to Sonic Adventure, but it was far too similar to Sonic DX (with E-Gamma and Big the Cat being characters). Among these, I think Sonic Adventure 2 is known best for the soundtrack, which make the millions of stages more enjoyable. On a short note, the Chao World is also more easily accessible in Sonic Adventure 2.
This game is definitely in my all-time top 10.
*All opinions above, such as the claim that Sonic Adventure 2 is the best Sonic game (especially that one), are those of Emmaline Shettel and most certainly do not represent those of GameLuster.