Answer:
I would choose Robespierre's side, because he was opposing the Old Regime, although he later did committed certain number of crimes after Louis XVI was dethroned.
Step-by-step explanation:
I wouldn't choose Louis XVI at all because he was incompetent as a ruler, and didn't care much about the needs of ordinary people. He even was about to call foreign armies to help him in fight against. Robespierre wasn't perfect at all, but was still fighting against the old regime, which brought so many problems to the country. At the end, he was also removed because of bad things he has done.