It took me a lot decide about it but... The rebels are SEPARATED. Mike has good intentions but is not a Good Strong leader.
Choose the Government side. Is this country Nobles fault that the Slaves live in such poor condition.. The war showed it that is their fault that Dorgania continues in such condition and the War will probably make them lose their position after Central Victory.
Rebels are people with DIFFERENT IDEAS about how obtain peace.. Follow the Rebels path without save and you will see how crazy can be that people to the point that you see slaves thinking that they are making their lives even worst. They recruit whoever wants to join them and leave the rest here.
They ruined
For the rebellion own good soldiers and other people(included slaves) lifes with their actions. They can be like bandits sometimes.
Even in a War situation
one of your spies does not recommend you ally with them... The Rebel leader that your spy finds wants the country control just for ally with you.
Also in this WAR ENDING