In case you couldn't tell, Sonic Underground, against all logic, is my favorite of all the Sonic cartoons. If you don't take it TOO seriously, it acts as a nice middleground between AoStH and SatAM. Plus it has Knuckles. And Dingo! Good lord does it have Dingo. And Robotnik is at his most charming too.

While Sonia can be a bit grating, I can't help but love her. Such a upper-class badass with a piano-shotgun and a motorcycle! If only she weren't voiced by Urkle. XP