At face value this often seems like a simple question.
If you want a Gun Ship then take the Assault Frigate.
If you want a carrier then take the Assault Frigate.
if you want to get in close then take the Scout Frigate.
Except this doesnt seem right. The scout frigate has 1 less red die than the Assault Frigate and a more evades lending itself to being a long range gunship in its own right. So why do we love Assualt Frigates with Ackbar so much? When does the Scout Frigate come into its own? If you really want to brawl the Torp Frigate seems like the cheaper option.