What kind of DLC I like usully depends on the game. Like, I really like MoTA in DA2, but that kind of extraneous side quest DLC wouldn't really have worked for me in DAO. In DA2 it was fine to go on a romp in Orlais cuz, wtf else is Hawke up to? Just bumming around Kirkwall. But in a game where the whole point is you're on an epic adventure to defeat the Big Bad, it would just seem weird to have that kind of random side trip. Kasumi in ME2 kind of sidestepped that, since Shepard needed to recruit her, but it still seemed weird to be at some random rich dude's party while evil aliens were kidnapping entire colonies of people.
I'd really like more DLC like the Shadow Broker, or like Leliana's Song but with your character still playable. DLC like The Exiled Prince/Kasumi/Zaeed is nice, but I'd like more that expands on the original companions. Like, say, a story DLC where you go with Varric to Orzammar to, I don't know, do dwarfy things. Basically, like really big versions of the DA2 companion quests. And yes, I would totally have played Garrus Vakarian: PI. Oh man, now I'm imagining an ME adventure game, like Gabriel Knight but with Garrus. Ha, and Shepard could be his Grace.
Armor/appearance DLC just annoys me. Doesn't stop me from buying it

But it's kind of irrititating having to pay for clothes, though the Mass Effect series is worse about this - you have to buy the appearance packs if you want certain female characters to have clothing options beyond skintight and totally impractical catsuits.