Also it is absolutely criminal to not mention BTA here, I'd write something but Spoon already said it 90 times better than me:
Between the Ashes made by mjn.mixael, is basically what an official Freespace 2 expansion pack could look like. Its a fully voice acted campaign with some incredible mission design and a compelling story, which all takes place in a single star system (with a starmap that you can look at from the main menu, which updates as the campaign progresses). It does an great job of showing you the civilian life side of things, as your GTA battlegroup gets entangled in a fight with a incredibly cunning, Hammer of light admiral. The mission variation in this campaign is just amazing. None of the old boring escort missions that involve fighting off 20 waves of pirate fighters here! Instead you get to hijack some poor sod's fighter by remote hacking and use it to attack the convoy he was hired to protect, to ruin his reputation. In another mission you get to prepare your defenses for an incoming attack by manually placing sentry guns and shields and such. There's just too much in this campaign to just easily sum up.
(note: this endorsement is in no way shape or form related to the badge i appear to have suddenly gained out of thin air