I wanna vote for both 1, 2 and 3.
Anyway, what I'd
like from a DLC is one that actually expands on the actual game. (Not past the main quest but rather just flesh out the rest of the game.)
But I know that won't happen, they'll all be toy-box DLC's leading up to the real DLC with Ulysses.
So what I want from these game within a game toybox DLC's is choices, a reason to play through it more than once or twice.
I want that the maps are at least as sandbox'ish as Dead Money was or maybe even more to Point Lookouts extent.
I want at some point new companions that I can bring back to the Mojave Wasteland.
I want more perks and traits but no more
forced level caps.
But a more general design I'm interested in is: Allow me to go back and give me a reason to go back.
Wether it's side-quests, hidden stuff, collectibles, allow me to go back.
And next up is for the story to have a good branching out design which allows for greater replayability.
And thirdly: for [censored]s sake don't unbalance the game with forced level caps or forced perks or overpowered weapons.
Most importantly though: More Legion, I think every DLC should have some Legion character or a connection to Legion in order to flesh them out then go out with a big bang and do a full Legion DLC.