I bought black ops 2 recently and there is still plenty of servers to chose from. Not much point getting the expansion packs though as there is hardly any servers with people playing them. The zombies mode is a bit dead though which is a shame.
Battlefield 4?
BF4 is £8 so not bad, whats it like to play online? Does it have a good following?
Yeah BF4 has a huge following. You wouldn't have any problems finding games to play. If you want the full BF4 experience you'll need to factor in the price of the premium DLC pack though as well.
Get BF4 you wont regret it!