There's playing Battlefield and there's playing Battlefield.
That may sound patronising, but when you get playing with people who know what they're doing, can help you with your technique and will help you out and become your buddies, the team work aspect, the large set pieces, the different ranges of gun fight you can have, the tactics you and your team and deploy, the differing methods of gaining the upper hand over the other team...
I don't understand why anyone over the age of 14/15 would play COD over Battlefield. It literally does not make any sense to me..
I'm going to link you to a video of a guy called FrankieonPCin1080p; He's a big nerd, but he's good at any shooter. He's playing with a guy called Jackfrags, who is also good.
But watch the gameplay (10-15mins of it) and tell me that COD can replicate the excitement of it.
Here's the link;
http://www.youtube.com/watch?v=5t7XUq_6nhw&feature=c4-overview&list=UUxbivvwPkudpfWrLQHGHQyw