I need to go through and see if any of these are worth mentioning. https://www.youtube.com/watch?v=qR_GmG0bcro
Topic on Talk:Sonic Adventure 2
There's a decent number in there, just at a glance. Trackable Emeralds and Faster Spin Dash seem like useful QoL mods for example.
Trackable emeralds and Faster Spin Dash is a feature in SA2 Mod Manager already.