Basically, you can major in anything and be eligible to apply to medical schools, as long as you complete all prerequisites as other application requirements for the programs you apply to. I would say major in something you enjoy, because undergrad years can be a perfect time to explore, and it's no use if you don't enjoy your major.
This professional recommends the following next steps:
- Make a list of all the majors you would consider
- Think about an make notes of what you think you'd enjoy in each of the majors and why
- Look at the list and see which one you think you'd enjoy most!