hmm well i like the fact that they are mostly basic shapes?? i mean anything you draw can be on basic shapes, but Sonic characters in general are circles and noodles..although i know is not that easy for everybody XD beyond the basic structure there is some very difficult things to draw on them, but i love that Sonic characters follow that kind of design, i mean they are very close to draw Mickey Mouse like characters but they also have some part of anime style too.. its like.. they are so simple and yet complicated at the same time.. dunno if anything i said made sense lol

also for a more simple answer…what i like the most about it drawing them its when i have to draw their faces and expressions.. i just love when i’m on that..