Best parts of Sonic Games?

I've heard read repeated arguements over the internet over which Sonic game is superior. Sonic 1, 2, 3K, CD, Chaotix etcetc. However, I'd prefer to take a deeper look. What do you think is the best game for things such as Level Layout, art, gameplay, etc?

An example of what I mean, would be
Sonic 3K is the best for artwork, as it delivers beautiful and completly different backgrounds and foregrounds for each Zone.
Sonic CD is the best for music, as the beats are catchy and matches up perfectly to each zone.*
etcetc

Please don't argue over different opinions. This isn't limited to the Mega Drive games, either. It can be from the Master System games up to the Current Gen games.

Sonic Unleashed in Art.
Sonic 3 & Knuckles in Platforming.
Sonic Unleashed in Speed.
Sonic Next Gen in Music.
Sonic Sega Tennis in Family-fun factor.

Sonic 2 in music
Sonic 3 & K in stage design
Knuckles Chaotix in multiplayer

Sonic Unleashed art
Sonic Adventure speed
Sonic Adventure level design(for the Sonic stages)
Sonic Adventure 1/2/Battle story and caracters

Yeah, I would say that.

Sonic Unleashed ... damnit. So many good things.

SA2 ... Atmosphere?

SA1 ... Hubs...

Heroes- level design

Shadow- Numerous number of humongus levels

Crystal Chaotix 3 wrote:Sonic Unleashed ... damnit. So many good things.

SA2 ... Atmosphere?

SA1 ... Hubs...

Heroes- level design

Shadow- Numerous number of humongus levels

Yes, I forgot about that.

Well, for the old games the music is my favourite part, I'd always try to get to certain levels just to hear my favourite songs, I love catchy, retro sounding music.

For the newer games, the cutscenes are my favourite parts. I guess it's because it feels like I'm watching parts of a Sonic movie or something. While everyone else is looking forward to playing the new Sonic games, I look forward to watching the cutscenes on YouTube! XD

Really, the best parts of all Sonic games are when the cutscenese happen and I get to see my favorite characters develop.