Everything we’ve seen of the F5 seems to have Edward as their lead.
But why use Edward in that position? Although he was eager to do everything he could to save Lizzy and the first recruited, he said he couldn’t sing or dance. In fact, Ciel seems to think the fact that Edward is a good looking young man of high status to be more important. If it was purely on talent, Soma should be the lead. He had natural talent and was even shown to help Edward. So, why Edward?
I think it has to do with their reasons for joining. Soma did so to help Ciel, and Joanne joined because Sebastian asked him to do so. Cheslock joined because it looked like fun, and Clayton said something about not wanting the former P4 from sinking further.
Edward is doing this not only to help Lizzy but to save Lizzy. He joined the group for love. It could be argued that his reason is more pure and he has the most riding on the group’s success.