Hi there,
Congratulations on some amazing undergrad acceptances! This is a good dilemma to have! However, I don't recommend basing your school selection on which program will maximize your chances of M7 MBA admission. The MBA admissions process simply isn't that cut-and-dry and there are aspects of your application that will be much more important than the name of your undergrad institution. My advice to you is to attend the school that will best position you for post-MBA success in your career. What school offers the classes, professors, alumni network and career management support that you'll need to get your dream job post-graduation? My guess is that the best school (UC Berkeley) is going to open more doors for you career-wise but that's something you'll need to determine for yourself.
The top business schools have representation from a wide variety of undergrad institutions and majors so there's no "best" one - again, I would choose the major and program that is best aligned with your interests and goals
However, I'm curious why you're selling yourself short on your UC Berkeley GPA vs. UC Irvine, for example. I doubt you'll find the curriculum to be SO different that you could pull off a 3.5 GPA at one school but only a 3.0 at another. My advice is to commit yourself to your studies and doing what it takes to maintain a high GPA no matter where you go to school. That will not only help you with MBA applications but also in job placement in the shorter-term.
You have a long way to go before you're ready to apply to an MBA program so I would focus on doing your absolute best in whatever school you choose, land your dream job after graduation, excel in that role, and then re-visit your MBA plans. Remember, "what" you've done is going to be less important that "how well" you've done it when it comes to your MBA applications.
Best of luck!!
Kindly,
Melody