SADX PC has a bunch of great mods that are worth tracking down, particularly for the restored Dreamcast assets/effects and Windy Valley prototype level.
Colors DS has a lot of the Rush DNA in it, but it's definitely a bit slowed down by comparison.
I'm pretty sure Sega could make bank with a formal Rush 3 at this point, if Dimps remembers how to make them.
And yeah, IDW Sonic's not bad. The writer's been working on Sonic comics professionally for thirteen years now, if you can track down any of his Archie material at this point.