It depends on what kind you like.
For more vehicle oriented combat , BF3 ot Black ops 2 isn't a bad choice if you haven't played mw3 or mw2 or Black ops 1 before. Otherwise it may seem like the same old same old.
Oh also if you have a few friends who have good PCs and like Online FPS like you then you should definitely get Planetside 2. It's free and it's awesome.
For me it can get boring if I'm not playing with my friends but then again , that's why I suggested it if you have friends willing to play.
But there is no single player though.