I guess it would depend on what tupe of pkaystyle you prefer. Some people look the whole run-n-gun, speedy gameplay of Call of Duty, and other, like the more tactical, think before you shoot (Ok, fine, it's a bit more run and guj than that.) situations of Battlefield. I always thought CoD rounds went by way to quickly, if one guys was really good, and the oposing team could even aim in the right direction, but Battlefield seems to taylor more to both. You can have the run and guns charging up hard, and the more conservative guys laying back, picking people one at a time. If you did that on CoD, you'd get yelled at by a 1st grader claiming you "hardscoped" (sniping how you're supposed to), were "famping" (protecting an area to force the other team to use different routes.). What grinds my gears about CoD is that when you do something that would be greatly appriciated in real life, you get bashed because aparently you don't fall into the catagory of the CoD elietists who believe it is unholy to aim down sights with a sniper rifle.
Sorry if I carried on a bit to much there. In a nutshell, CoD has become one of those games that players have twisted the game style so much, that half the stuff that would work in real life gets flip flopped to the oposite thing. Call of Duty, the only game where guys on the frontlines use sniper rifles, and the guys picking people off using sub machine guns.