We went 7/4 week in 2017. 7/4 was a Tuesday. We were in/around the MK both days. Watched fireworks from Poly but went to MK afterwards both nights.
In many ways, I 'felt' 7/3 was way busier crowd wise. Since 7/3 was a Monday, it almost seemed like that was the "holiday" for everyone. Since most folks have to go back to work 7/5, I think 7/4 may not be quite as attractive for locals.
Obviously just a generalization, of course.