G. Mark’s Answer
Well, the first thing is the obvious -- electrical engineering. But from my point of view, I'd say a lot of majors will have applicability in the field of EE. I started out with a scholarship that assumed I would become a doctor. I was in pre-med when I happened to be walking down a hall in my undergrad college, Wayne State U. in Detroit, and I heard a lecture on a television monitor that sounded intriguing. It was something about a machine that behaved like a "monkey in a box", and that was about computer science. I walked in and stayed for the entire lecture and ended up in CS.
I ended up being recruited by Bell Labs and got into a program that would pay me a salary and pay my grad school expenses so I could get my MS in less than a year, and it seemed like a great deal. Something I learned in those months was that 1) I had a lot to learn about EE, and 2) A lot of what I'd learned in other fields from liberal arts to science to physiology surprisingly came in handy at surprising instances to solve problem, build machines, communicate with other people, etc., etc. And this continued throughout my career.
It turns out that it's estimated that about 70% of innovations are generated by applying knowledge from fields other than the one the original problem to be solved seems to originate in.
So while EE is the "best" major for someone interested in EE, don't count others out. Because human knowledge and achievement is as general as the human condition itself.