Simply put, if everything else is equal, there is still likely going to be a gut reaction based on the photos - with one lady edging-out the other.  We are just very visual creatures.  If not, and it's really a true tie, then something as mundane as the location of the incall will make a difference.  For instance, I'm a DC suburbs guy, so if the incall is in the MD or Northern Virginia suburbs, I'll go with that over downtown DC every time.