Well, I love CA's Fireteam stuff, it's alot better than Crossfire's in my opinion. However, CA doesn't completely cooperate with my graphics card, so i tend not to play it. CA also has way to many updates on events and things, as Nexon is a money leeching machine and they try to get as much money as they can. CA Is all about spraying to me, nothing really registers.
CF on the other hand has an easier interface and updates that people can easily get into comfortably. I like CF's easy game play because it feels fluent and you move really smoothly around the map. CF Has poor graphics, but that's good for people with bad computers. Crossfire has an easy recoil pattern to get used to, and the bullets register a little better than combat arms. Sniping in CF is also really OP too, the scope activates instantly.
I have lots more to say but, i prefer CF nonetheless.