For me it was a tie.
When I first got the hang of this game, my fleet was just my starter Wolf Class Assault Frigate (which I adore) and another Wolf Class Point Defense Frigate. So while hunting pirates for some cash, I stopped paying attention and flew straight into a Pirate fleet of a bunch of shield-less destroyers, a couple of light carriers, 4 wings of assorted fighters, and a battlecruiser. So I picked a single point and captured it, set my wing-man to escort my flagship, and waited. I figured my escort would give the fighters trouble so I could pick them off before they ran away, all the way weaving away from the bigger ships. With the fighters out of the way, I got my escort to take care of rockets while I
exploited used the Wolf's long laser beams to pick of the shields of the carriers before sending in harpoons. The shield-less destroyers I just took out their small arms with the Graviton beam and harpoons made short work of them.
Seeing how awesome my fleet was, the Battle-Cruiser starting running like a smart little Pirate commander he was. Boarding the ship after it Surrendered would have got me a good credit turn-in. But this was not that Pirate's lucky day, after this battle I was in a killing frenzy. I shot at this ship's engines until they burnt out, I managed to kill some of the carriers with energy weapons so I had about 4 harpoons left. So I unloaded on this poor man and 4 seconds later the screen flashes with a huge explosion.
My other close tie would be with the Gun Runners mod, using a Assault variant of the Gun Runner Medusa clone.
I had lost my trusty old Wolf frigates when I first tried my new Gun runner ship, letting the AI forget about using shields
So I bought a Gun Runner Cruiser and a couple of fighters, forgetting all about getting more crew. So I picked the largest Independent fleet I though I could take on with my new cruiser. The fleet was running but I caught up, I also forgot to save before fighting but I figured I had a guaranteed win...
So the combat screen comes up, and I only see one ship! There was at least 5 wings of fighters on me in about a minute, this ship had a needler which works wonders on enemy shield flux but can take out bombers in one burst.
For some reason the Needler does not run out of ammo on my ship, however once I took out all of the frigates and fighters, the only weapon I had with ammo was the Needler. There was 2 light carriers and one cruiser left, my weapon could over load a carrier in 2 bursts, 5 bursts for the cruiser, but did minimal damage to armor. After 3 minutes of fighting, none of the ships had taken any damage so the decided to run away. The cruiser surrendered, and the carriers escaped.
I took out an armada, solo. Twice. So I guess really it was one experience