Fireteam seems ok if you are on Extreme and kill at least 50+ terrorists. You'll earn a good amount of Exp but GP tends to be lower
S&D with at least lets say 10+ kills and no more then 5-7 deaths will earn between 150-300 Exp and at least 250+ GP
Elimination is good if you rack up at least 20+ kills and less then 15 deaths. Usually get 150-250 Exp and 150+ Gp depending on the game.
Quarantine to me is only good if you come in the top 5 players, meaning you score at least 120 points, THEN you earn a good amount of Exp and GP. Best place to survive is of course Two Towers.
So if you're willing to put some time into it do S&D, Fireteam, and Quarantine. For quick matches do Elimination.
Hint: For Elimination you earn more if the match is set for 140 kills