The only way I can try to justify Battlefield currently having more votes than MW3 is:
1) People voted without reading the OP and thought he was asking which one they preferred
2) Those people were thinking PC only
There's simply no way Battlefield will outsell MW3 in total. The console gamers are way too stuck on that franchise. It will be a year or two before Call of Duty starts to slip if Activision doesn't do anything to refresh the series.