Why does Call of Duty have more fans when Battlefield: Bad Company 2 is better? and the 3rd looks ridiculous?

I have modern warfare 2, and black ops, but when I bought Battlefield: Bad Company 2, I was like wow, it's way better. The graphics on Battlefield destroy any call of duty game, and the game is so realistic and fun. I love the style. If I compared the 2, I would say battlefield has more fans, but that's not so. I was wondering why? do u think its cause of the quick style of call of duty that everyone likes it more