I want expanded gameplay and REALLY excellent maps. Borderlands does a pretty good job with new classes and about half of their map content is decent.
What sucks is when you get a good base game, and then a mixture of good/great and mediocre DLC. It's like they intentionally do it to earn your trust so they can exploit it with a shit DLC or two.
This is just ignoring all the bugs and imbalance that comes with the DLC/base game. I am also not a fan of a lot of aesthetic stuff being sold as CONTENT. It needs to be called something else, skin packs...something to indicate it's ONLY a reskin of something with no additional functionality or use. You have to really dig to find out if that's the case or not on some of these preorder bonuses, etc.
And all that said, mediocre base games and mediocre DLC basically forces you to wait for other people to buy it and get the "new shiny" out of their system so they can review it properly. So that's a month or more depending on the game. At that point you've lost your chance to maximize the money you're getting per unit by not keeping your content interesting and well designed. Once you fall behind the tide of new releases, it's pretty easy to get stuff on the cheap and keep yourself entertained with a lot more games at much lower prices.
This is only PC gaming, I haven't done consoles in a long long time.