Battlefield: Bad Company 2.
The series was not big back then, but it has EASILY the best single player campaign from the Bad Company series, with extremely likeable characters, awesome graphics/destructibility and some awesome set pieces/settings.
Not to mention it is the best multiplayer in the Battlefield series. Arica Harbor will forever be the greatest map. I don't even want them to try to make a Bad Company 3, because pretty much none of the key people who worked on BC1 and 2 are even there anymore...
It sucks most people will never experience the greatness that is Bad Company 2. I actually tried to play BF3 and BF4 single player campaigns and holy shame they are god awful. IDK what they were smoking when they made that shame.