Corellian Gunship wolfpack > anything else
I wish I could remember who in these forums recommended this strategy to me, or remember which thread it was posted in. Maybe they'll come by and claim this strategy, because it's certainly theirs and not mine originally.
With ten gunships and nominal reinforcements (ten or less) I've been able to beat any Imperial fleet on hard difficulty. And my kill ratio is extraordinarily high.
I use concentration-of-fire on the biggest enemy units (i.e., ISDs), then attack-move through everything that remains, then kill the space station last (if I'm the attacker). I might snipe the hangar if it's a lvl-4 or 5 station that's generating Acclamators. Otherwise I ignore it until everything else is dead.