I have an affinity for jazz, so a lot of my picks will lean in that direction.
A lot of Sonic Mania's original compositions are pretty ace -- particularly Titanic Monarch 1, both acts of Press Garden and the entirety of Mirage Saloon. Tee Lopes does a really good job of coloring the kind of soundscape and compositional flow you would expect from classic Sonic, but it's still distinctly his flare. Highlight for me is probably
Mirage Saloon K -- kickass level and a massively overlooked iteration on the motif. Mania also has without a doubt my favorite
Metal Sonic theme from any of the official games.
I feel like on the whole I prefer Sonic Adventure's soundtrack over SA2's, but the SA2 Sonic stages do have a lot of memorable themes, and Shadow's portion is solidly produced; that being said, I think Rouge's entire portion of the soundtrack is criminally underrated.
Security Hall IMO is iconic as anything else in the soundtrack. Also shoutouts to
Mad Space for its 7/8 shenanigans.
Sonic Unleashed has some fantastic music all around; probably my favorites are honestly just the hub world music (e.g.
Apotos and
Spagonia), but the real highlight has to be
Arid Sands (Night). Absolute jam.
Last pick,
The Wicked Wild from SatSR. This song slaps, and anyone who disagrees is cringe.