Why is everyone saying battlefield 3 is gonna be better than mw3?

Everyone is flaming mw3 and saying battlefield 3 is gonna be better but how do they know, battlefield 3 hasnt even released any info yet. Is it because mw2 was unbalanced, cause i know in mw3 they are most likely gonna fix it, they were going to fix mw2 but couldnt because infintiy ward got sued. But imo i think mw3 is gonna be better because cod games last me forever but even though battlefield is good it still didnt last me as long. To sum it all up though, im gonna get both, and both are gonna be amazing :D