Higher GPA trumps all. The consensus here on SDN is that a 4.0 in something "easy" like a humanities major is equivalent to a 4.0 in something "difficult" like an engineering major. Majors can't be compared objectively because the notion of what's easy and what's hard itself is subjective.
Similar applies for easier and harder classes. The lower-level classes are misinterpreted to be easy because the content is introductory. That is false, because the classes can test very difficult material and graded on a very harsh curve to weed out premeds and careless students. Harder classes involve difficult material and the exams will be difficult, but students will be exposed to the curriculum by then.
If anything, a 4.0 on upper-level classes help to alleviate the negative 3.0- impact on a lower-level class, but that's rare. But because there are so many subjective factors involved, adcoms aren't going to waste their time scrutinizing thousands of applications determining what is easy and hard. The high GPA is an objective assessment in these cases.