Pre-Med: Which undergraduate major is best?

I want to pursue Medical School or Dentistry. For undergraduate, if I pursue Engineering, particularly Computer Science or Data Science then chances of GPA below 3.8 out of 4.0 scale seem to a risk. It seems majoring in Biology only will mean I am one of the many that apply to Med school.
Which major do you advice I pursue so that (i) I end up with a good GPA (assume I am diligent and will work towards my goals) (ii) if for some reason, I don’t get into Med School or Dentistry, what options do I have so that I can secure a good paying job similar to CS graduates (iii) what is your advice on pursuing Bioinformatics - is that grade deflater as a major to pursue?

Although medical school admission officials certainly do look at overall GPA, their priority is to scrutinize the grades earned in the pre-med classes. This approach is a great equalizer because the student majoring in, say, astrophysics (known to be a brutal choice on many campuses) will take the same pre-med classes as the student majoring in elementary education (not typically as grueling). Sure, the choice of major CAN affect the cumulative GPA, and med-school admission committees consider this too. But they don’t consider it in isolation.

If you like working with numbers, bioinformatics is a hot field right now and you may even discover that you prefer sticking with it rather than going into health care. Other number-crunching fields like Data Science and Actuarial Science are hot right now, as well, and often lead to good jobs straight from college.

But it concerns me that, although you say that your goal is to be an MD or a dentist, it seems like your motivation is mainly monetary. Because med school and dental school are highly competitive, it does make sense to have a back-up plan in case you don’t gain admission. But when applying to medical schools, you will be expected to demonstrate compelling interest in becoming a doctor, so your first step is to ask yourself some tough questions about why you’re REALLY choosing this career.