Spring Yard Zone
https://www.youtube.com/watch?v=cDd_GlynA6A
I like this theme a lot because there's a sort of playfulness in its tone, as well as being a bit of a swanky tune.

Casino Night Zone (2 Player)
https://youtu.be/7NyVZF0HW_U
Once again, I just think this has a pretty swanky beat that I vibe with a lot.

Cosmic Eternity ~ Believe in Yourself
https://www.youtube.com/watch?v=5AW7xQ_Dxjk
Sonic CD's ending credits theme is a major highlight of the OST. My opinions on CD aside, I think it fits the game superbly. Sonic CD is a game where you essentially try and create a better future for Little Planet, and the ending theme reflects that. It's a song about facing the future head on, an optimistic song that feels like it's trying to cheer you up and having a heart-to-heart with you about what to do going forward. It feels like a good representation of the Classic era of Sonic. It's a hopeful and empathetic track that represents his character well and plays into the theme of time and what to do with it.

Lava Reef Zone Act 1
https://youtu.be/nyNzyyxmAwM
Despite the general nature of the setting it's used in, this is probably the most chill track in the game. It's oddly soothing in a way I can't describe.

Staff Roll
https://youtu.be/ezLGTcdZU8Q
Not really much to say, I just like how it sounds.

Never Let It Go
https://www.youtube.com/watch?v=ZhjzUqHSKQ0
This song just rules, feeling like the epitome of "I'm done with your shit, let's just beat each other up" and just going with it.

Living in the City
https://www.youtube.com/watch?v=VO7OwIhfBjE
Sonic R's soundtrack is fantastic, but Living in the City takes the cake for me. It's nice listening to this as I race, and there's this mesmerizing feel to the instrumentation here that isn't as prevalent as it is in the other tracks.

Be Cool, Be Wild, and Be Groovy
https://www.youtube.com/watch?v=lGArZbIGoNo&t=1032s
This song feels like an intense rush. It embodies this era of Sonic in a way, carrying this high-octane yet carefree energy to it that the era exemplified.

Live and Learn
https://www.youtube.com/watch?v=z1BRZg0GG0A
I'm a basic bitch for putting this here, I know, but I like the buildup the game does with this song, only hearing bits of the instrumental version throughout the game, and then finally at the end it plays in all its glory as you fight down a planet-destroying lizard in what is honestly a pretty bad fight. Live and Learn is one of the most recognized tracks in the series for a good reason. Its lyrics are esoteric, but they hold immense power behind them, ultimately used as an inspirational song meant to convey the message of holding on to hope in the most dire of situations.

Egg Rocket Zone
https://www.youtube.com/watch?v=yTbwj3dLO1g
Egg Rocket Zone has an energetic yet melancholic feeling to it, a reminder that you are nearing the end of your journey, tinged with a determination to see everything through. It's a great track that deserves a better stage to accompany it.

Ice Paradise Act 1
https://youtu.be/mM8Oy3i1wV4
This is probably my inherent bias for snow level themes poking through, but I kinda vibe with this track.

Nonaggression
https://youtu.be/CKwOqIGvs2g
I'm gonna be honest, most of the final boss tracks in the Advance trilogy are very forgettable, but Nonaggression sticks out for its sheer intensity. Gemerl, a corrupted version of Emerl from Sonic Battle, is the final confrontation of the game, and the music makes it out as this do-or-die sort of fight. It is intense as I stated before, but from the arrangement, it's more of a need to save someone and not just stopping the villain of the week. It's a good song elevated immensely by the context it's used in.

What I'm Made Of
https://www.youtube.com/watch?v=ScvxT0RItYE
This song just fucks, plain and simple. What I'm Made Of is Crush 40's best song by a landslide. It feels like a track that can only really fit Sonic, as I feel it is the embodiment of his character. No other vocal track characterizes him in a way that this track does. It's cocky, yet determined and hopeful. Not only is this the best vocal theme in the series in my opinion, but is is one of the best vocal themes of any game I've ever played, up there with the likes of Burn My Dread (Persona 3), The Key We've Lost (Xenoblade Chronicles X), and Mirror of the World (Guilty Gear Strive) for me.

Never Turn Back
https://www.youtube.com/watch?v=nEFknRfCDQ8
Never Turn Back was, for the longest time, my favorite credits theme in the series, until recently where it has been dethroned by another track I'll get to later. With that said, I feel this is a great crescendo to Shadow's character arc. It starts off melancholic with a piano solo in the beginning, but it progressively evolves into a song about facing your past head on with all the confidence in the world and becoming better than who you once were. Shadow, a being haunted by his past and unsure of his placement in the world, comes to terms with everything and carves his own identity, and this theme represents that. Despite being unsure of what the future holds, it's about showing the world who you are and not looking back.

Aquatic Base Level 1
https://www.youtube.com/watch?v=dEHuZpITceY&t=55s
This song is honestly just peak vibes for me, a wistful and lowkey track as you explore this underwater base. True story, I would go to sleep to this track often. It's just that soothing.

Vela Nova
https://www.youtube.com/watch?v=-7WQn-SXYZ4
Despite being composed by someone whose Twitter account is a war crime, I vibe with Sonic Rush's OST a lot. Vela Nova in particular is a highlight, being a sort of jazz-sounding track with fitting vocal samples in the background as you fight the character opposite to you. It's a good representation of both Sonic and Blaze, having a fast-paced beat to it that Sonic songs are known for, while complementing the jazz-like composition fitting newcomer Blaze.

Sky Babylon
https://www.youtube.com/watch?v=tsDVRJMYEYE
I don't know what to say, I just think this track is real neat.

High and Broken
https://www.youtube.com/watch?v=b7FmmOCB2p4
Secret Rings' OST is a mixed bag for me, as I vibe with about half of the tracks and could go without the other half. With High and Broken, there's this grandiose nature fitting of the setting the game takes place in. It's, for lack of a better term, epic. The sense of scale that the game goes for is enhanced by this song, with intense strings and percussion. For as much as I rag on Secret Rings, when the music is good, it's incredible, and this is the best the game's soundtrack has to offer.

With Me
https://www.youtube.com/watch?v=L9I9qsKJL5s
Sonic and the Black Knight is a game that, despite my many grievances with the gameplay, I just keep thinking about time and time again. The final boss, from a purely thematic perspective, is the peak of the franchise as it represents the fragility and stagnation of life and humanity, paired with a track that sees mortality as a necessary evil meant to illustrate the importance of life. This theme could be viewed from either perspective, whether it's how Sonic views Merlina or vice versa. It's one of the reasons I think so highly of Black Knight despite it all. With Me is an intense theme that brings the themes of this game and arguably the series as a whole to the forefront, and it's the most somber final boss track in the series. It's a medley of conflicting ideologies and moral ambiguity, bringing forth the question of whether or not the goal of immortality is even ethical. Compared to how triumphant most of the final boss tracks are by this point in the series, With Me feels like a massive wake-up call and questions whether your own actions are just or not. One of the best tracks in the series easily.

Jungle Joyride (Night)
https://www.youtube.com/watch?v=UF3XUXWCxBs
Sonic Unleashed has one of my favorite OSTs of all time, and is the peak of the franchise for me in that regard. Jungle Joyride Night is an interesting track to talk about. There's an air of intrigue that permeates here, with the chimes at the beginning setting up that intrigue. Underneath that is a tinge of wistfulness displayed by the cellos and piano. While not exactly melancholic, it's a bit more of a contemplative and understated track compared to what you'd expect in a regular Sonic stage. It's a more low-energy and slow theme that evokes a feeling of introspection, as if to make you think about the current landscape and what it holds as you reach closer to the game's climax.

No.

Hell no.

This is a sick joke.

Planet Wisp Act 1
https://youtu.be/uFUSim9dvQw
Planet Wisp's theme feels adventurous, yet down to earth in a way. I don't have much to say, I just really like this song.

Ending Medley
https://youtu.be/nKAdQi_m0fc
This feels like a walk down memory lane, listening to a medley of the stages you played as the game comes to a close. It's like meeting up with an old friend as you both look into the future, wanting to make more memories for years to come.

The Deadly Six Theme (Violin Version)
https://youtu.be/_EPRRs31YjE
Honestly, this is the only track in this game that I can actually remember. Almost the entire rest of the soundtrack is so forgettable, it isn't even worth mentioning. I think it's telling how this is the best track from Lost World, yet it doesn't come close to the rest of the music on this list.

Infinite
https://www.youtube.com/watch?v=LDu9AY15fQI
This is probably the second worst mainline Sonic soundtrack overall for me. Almost all of the vocal themes are pretty mid or straight up bad, and a lot of the instrumental tracks are forgettable and sometimes genuinely painful to listen to, with some exceptions. However, Infinite's theme goes extraordinarily hard. It's edgy as hell, but there's a tastefulness to that edge. Despite how nothing of a villain Infinite is, he's given an extremely memorable theme that remains stuck in my head after all these years. It doesn't really fit the tone of the rest of the game, but I'll take it.

Vandalize
https://www.youtube.com/watch?v=neexlOTmAxw
I have the inverse problem compared to Forces because unlike with Forces where I didn't like any of the vocal themes except for Infinite's theme, here all of the vocal themes bang, even in the Cyberspace levels. Probably the best set of vocal themes the series has had in a very long time, and it's where most of the strength of the OST lie. However, my personal favorite has to be Vandalize. It is a very melancholic song diving into a toxic relationship and the conflicting emotions it can leave behind. Essentially this is Uncontrollable from Xenoblade Chronicles X. Even when comparing the rest of the tracks in the series, vocal or instrumental, it's the most somber a Sonic track gets. I know I meme on the lyrics "Fuck the pain away" but the song as a whole is one of the few tracks that got me legitimately emotional, even divorced from the context of the game. Despite the nature of the song, I feel it fits in with the theme of reconciliation the game is going for very well. It could alternatively be seen as being someone stuck in the past unable to move on, much like how some of the cast aren't able to truly move on, whether in a figurative case or a literal case. The performance given by One Ok Rock solidifies that feeling of being in an unhealthy relationship and is one of their best songs as a result. In a way, I feel this is a direct contrast to Sonic CD's end credits theme, because whereas that song was more uplifting and about facing the future head on, Vandalize is more solemn and, as I said, could also be inferred as someone stuck in the past unable to move on. Funnily enough, these two themes are the only credits themes in the series done by Japanese vocalists. Best credits theme in the franchise bar none, and a strong contender for best vocal theme in the series.