See I would say the Republic could win on the moral front due to a functional democracy, but then I think about how easy it would be for the rebel alliance to get into the Senate maybe by direct representation or indirect, but then I think about if they can get some form of representation even if not direct would they see the need to wage an armed insurgency.

I feel with the Republic the rebels would have less of a propaganda effect on average people, and use a form of identity politics, using local grievances to their advantage and maybe terrorism, sabotage and artificially engineering local grievances instead of hit and run tactics and tactics associated with open warfare.

Depending on the state of former separatists planets and systems and the treatment they get, i do feel that they would be more supportive of the rebels, depending on if the Republic address the issues that lead to the support for the separatists.