By "best victory" do you mean most epic battle?
Well, one time (playing as the Imps) I was attacked while on Atzerri by an enormous Rebel fleet, unfortunatly my fleet which normally would be guarding the planet was occupied on Endor and I had only a level 2 space station, obviously I lost because of the barrage of missiles from their marauder cruisers. After the battle was over I quickly moved my fleet orbiting Endor to Atzerri to engage the enemy before they could land ground forces, I won the battle (pretty quickly too) thanks to my swift tartans wiping out all of their sluggish marauders before they could fire.
After the enemy fleet was decimated I returned to the galactic map to decide where to strike next just then another fleet engaged Atzerri! But...the enemy fleet was the ground forces sent to take Atzerri, There at least 25-30 transports in their fleet. I simply activated the interdicters and my tartans wiped them all out. I wiped out at least a 1/3 of the total enemy army with one swift move! THIS was my finest hour!
"You will pay the price for your lack of vision!" - Palpatine