That's the tough question really. Evolving this topic further, let's look at a few key moments in history where the situation is in doubt and we get to decide which 'side' we are on.
Let's say 50 BC. Caesar, the de facto leader of the Populares has conquered Gaul but has not crossed the Rubicon. The Optimates, backed by Pompey in a military sense, still have considerable power of their own. The eventual winner is clearly in doubt, who then would you back. As I said earlier I love the history of Caesar, but who I supported at that time would depend on my personal conviction and my station in life. Despite admiring the 'greatness' of Caesar, compared to the bungling of the opposition, I believe I would've supported the Optimates had I been among the elite.
As another choice, try to make sense of the turmoil following Caesar's death. Antony is the default new leader of the populares, but lacks Caesar's charisma. Cicero tries to prop up Octavian as a new leader of the Optimates. Lepidus, the leading patrician left alive, had his own following. Who would've known that Octavian would turn against Cicero and ally with Antony (even though he called for justice against the assassins quite early)? Even after the triumvirate was established and the 'Republicans' were destroyed, who would've guessed that Octavian could beat Antony in an actual war. In my previous example, I backed the Optimates. Had I survived, I would've likely ended up with Sextus Pompey (great I was once a Senator, now I'm a supporter of a pirate), but lets say you are forced to pick amongst the triumvirates. Pick wrong and you are eventually dead, Octavian was not so forgiving as Caesar (assuming your convictions are strong and you are not willing to switch sides mid conflict). Lepidus at least was a Patrician with a strong familial history. Antony and the way he acted (eastern influences) was an embarrassment. And Octavian was a johnny come lately with no legitimate right to power.