I'd say their a few but a big part of depends on weather or not you want to disqualify factions that are personally being lead by a protagonist... even as antagonists the most vile thing they tend to do is try to keep Nod fighting itself and tolerate Boyle... until they manage to find a legal way to get rid of them.
We do know that they explicitly relenquished control to an elected civilian government at some point (Boyle in large part seems worried about his electibility) and we do in fact see GDI from plenty of non-GDI perspectives... usually Nod who have a lot of reason to push the most anti-GDI narrative they can and even than GDI comes out looking rosier than say... the UNSC from Halo with their child soldiers for instance.The GDI is a military force, not a government. We don't really get to see what life is like in under GDI rule but... I have to imagine that's essentially martial law. I can't think of many times in history when the military took over and things were great for the average joe.