Its not that simple.
You need to take into consideration other governing factors.
TWS unlike MOS: Was a sequel that was coming off the Avengers, got rave reviews, and was released in a much less competitive timeframe
IM3 unlike TDKR: Was the first major Summer film released, had 3d and IMAX, and no shootings that hurt business.
Now on to BvS vs Civil War.
BvS will mark the first time Batman and Superman meet on the big screen, whereas Civil War will be Cap and Tony's 3rd meeting.
BvS will be released in the absolutely dead period of late March to the end of April, while Civil War will have to contend with other Summer flicks which won't be that far off.
Sure Civil War will feature a ton of heroes, and most likely Spiderman in the MCU, but BvS won't be short in the hero cameos, such as WonderWoman.
Of course there is no guarantee to which film will outgross the other, as there are other factors we can't call until closer to release, such as how well both films are market, and WOM, which play a huge part. These are both mammoth films, and a lot of things need to be considered, as to which will outgross the other.