This will be controversial as as far as I am aware it isn’t held in that high regard but in my opinion the best Sonic game made is Sonic Spinball.
It is an odd mix of things, there are a few sections where you need to do some very simple platforming but other than that it is basically a pinball game where you can influence the direction the ball (sonic) is travelling in a very small way. You need to hit certain objectives on each level to acquire chaos emeralds that then open up a boss room. I tend to return to it and complete a play through each year!
As a Sonic adjacent game I also always liked Doctor Robotniks Mean Bean Machine which is a match 3 type puzzle game where setting up combos of colours will trigger blocks to drop on an opponent and you have to survive whilst trying to push their game to the ceiling. Nothing ground breaking but I always enjoyed it.
Aside from that all of the original 2D platformers are decent and Sonic R on the Saturn was alright at the time, although not sure how it has held up over time.
All of the 3D offerings I have tried have been utter shite imo





































Hey, don’t bring me into this! ;p