I did play SA1 as a kid, but not much of SA2. Didn't play much Sonic otherwise.
Returning to SA1 as an adult, I was surprised how much I liked it. It's jank, but it's fun to control, music is great, side modes are novel. My only particular complaints are that some bosses are shared between characters, so you get tired of that one fuckin lilypad boss pretty quick, and Amy controls like shit from an ass.
Playing SA2, that one definitely survives more on vibes. The Sonic stages are still fun, the chao garden is great if you like that kind of thing, music is also still great, Sonic/Shadow rivalry is cool, but the mech and treasure stages are so fucking long and obnoxious like holy shit, and they just keep forcing you into them between every Sonic stage. Most of the game is spent doing clunky, slow mech platforming with it screeching BEEEEP BEEEEP BEEEEEP BEEEEEP in your ear, and running around needlessly large stages with a broken treasure radar. Douses literally any fun you have in the Sonic/Shadow stages.