I'd say Bioware or Bethesda.
Bioware because it added missions to ME2. but not ONLY that, it added characters, amour, and new weapons. Most DLC packs only come with 1 new thing. (Look aw MW2 or Halo 3 for example, just map DLC). And they did most of it for free. Which all DLC should be.
And Bethesda, because they basically do what Bioware does. The quality of the dlc can be questioned though.
Bioware because it added missions to ME2. but not ONLY that, it added characters, amour, and new weapons. Most DLC packs only come with 1 new thing. (Look aw MW2 or Halo 3 for example, just map DLC). And they did most of it for free. Which all DLC should be.
And Bethesda, because they basically do what Bioware does. The quality of the dlc can be questioned though.