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.
If your into fast paced games id look at crysis 3,bf3,and the cod games. If your into more tactical games than arma 2 is your best bet till arma 3 comes out.
I have found lately that bf3's netcode puts me off to much though, getting sick of being killed after I have ran into cover.Gun play is the best though.
Team Fortress 2 Is a f2P game and it has great class variety and it actually takes a little bit of skill. It has a great community and you it is great for competitive and fun matches.