FFA, TDM, Domination, S&D, Demolition, & ETC...
My favorite mode would have to be TDM because of the play styles you will encounter. It's also the first game mode I played when I first played a FPS in MW2 via Mercenary TDM. Spawns can be sporadic forcing me to learn them quickly (2nd to FFA). From what I've learned in TDM, I can apply it to every game mode I play. When I play objective games IDGAF about kill/deaths so I pick the best perks/streaks/equipment available to help the team win. I run specialist when I have no doubt about the enemy team =P
So which game mode(s) do you prefer & why?