What's so good about sonic? I'm being serious because I don't think that the platforming aspect is good and the characters are... annoying :(
Sonic at its core to me was a mix of platforming and racing mentality. Replaying levels to learn routes to get best times, sort of a short term way of speed running (literally).
I would say Sonic 1-3&K and CD were all great games that established the series as Mario's main competition. I'd also highly recomend the Sonic Advance Trilogy that feels like an extension of the 90s glory. The Adventure titles were solid, even if I really just like playing Sonic/Shadow levels. Why Generations was so great, it felt true to old 2D titles while bringing 3D into the mix.
The issue is have been some rough entries along the way such as Sonic 06, and since Generations Sega seemingly lost momentum with the Sonic Boom titles. I still have hope they can repeat Generations, and if it is more Boom I'll just pass.