Enemy Within for XCOM Enemy Unkown was a perfect addon. New storyline, new surprises and more polish to the main game. Well worth the money

The following DLC From dying light was great, new area, new mechanic (driving) and expanded on the story

Are we counting old-school expansions as DLC? If so, then, aside from the infamous Horse Armor, the Elder Scrolls series seriously raised the bar for what to expect from RPG add-ons. Tribunal and Bloodmoon were massive expansions that set the standard early on.

Knights of the Nine might’ve been a bit weaker, but Shivering Isles is one of the GOAT expansions and is arguably better than the base game.

Skyrim kept the momentum going with Dawnguard and Dragonborn, both of which added tons of new content.

The series is straight-up GOATed when it comes to expansions that are actually expansive: new locations packed with quests, items, monsters, spells, etc. They take already huge games and somehow make them even bigger.

Red Dead Redemption’s Undead Nightmare was excellent.

I quite like most of the The Binding of Isaac DLC (although sometimes they’re a bit too big, to be honest).

The Vietnam DLC for Battlefield: Bad Company 2 was also rather good. I didn’t get to play as much of it as I might have liked but I remember it being more than just a resin.

Bonus: Red Alert 2: Yuri’s Revenge (an expansion pack rather than DLC admittedly)

The Destiny and Destiny 2 expansions were great… right up until the one that removed 1/2 the game.