The major factor that tended to drive the decisions of African Americans during the Revolutionary War was which side they thought was a more likely path to freedom.  This is, of course, not true of every African American, but the majority of African Americans are believed to have made their choices based on what would promote their own freedom.

Both sides in the war, at various times, offered monetary rewards and/or freedom to blacks who fought on their side.  At other times, blacks fought in hopes that their service would allow them to become free or to gain more rights if they already were free.  Overall, then, the decision about which side to fight on was not typically based on ideology.  Instead, it was based on calculations about which side was more likely to offer tangible benefits in terms of freedom, rights, or (in some cases) money.