I think you are asking the wrong question. “Am I better off” with a lower GPA at a better school or a better GPA at an easier school… Well, you are “better off” working your tail off at no matter what school you are at. Don’t sell yourself short by assuming you will make a lower GPA at a “better” school. SAT scores have no correlation to how you will do in college.
That being said, the issue with school choice vs. GPA comes down to opportunities. For instance, like the previous post, I went to a state school, have a professional degree and make a LOT more money than many in my field from more prestigious universities. However, there are also a lot of people from prestigious universities making more than me. But it was a heck of a lot easier for them to achieve career goals than it was for me because they had more opportunities due to their pedigree. That degree from [Prestigious U] with the alumni network gave them interview opportunities that I never had. I digress, but where I am going is to say that it is a combination of things. Hard work at a university favored by recruiters in the field in which you want to study, research in the field, making yourself marketable to potential employers, impressing potential employers in the interview, etc. All of these are factors in your future employment that are just as important as the school and the GPA. The key is getting the interview or getting your foot in the door.