The Borderlands series does a lot of things well, but the thing it does best might be its use of DLC. Both games have some amazing longer-form DLC that brings in new characters, new story elements, and new locations. Choosing between these two was so hard, I decided we'd call it a draw and put them both on here. The Secret Armory of General Knoxx was the third DLC for the first Borderlands, and at the time, was the largest DLC Gearbox had made for the series. It included fights with Crimson Lance soldiers, the armory itself and its vast timed rewards, and of course, the dreaded Crawmerax fight.
Tiny Tina's Assault on Dragon Keep didn't build on Borderlands 2 as much as it took the game in an entirely new direction. The premise was that Tiny Tina was running a "Bunkers & Baddasses" game (in case you don't get it, it's a D&D reference) for the Vault Hunters to play in. As one of the characters in the game, you explore a fantasy world filled with skeletons, dwarves, dragons, and an evil sorcerer. In true Borderlands style, you shoot all of these things in the face. It's certainly my favorite DLC of all time.