I agree with other answers that all four schools are very good for a premed student.
This leads to three things to think about:
Of these schools, which one will make it easiest for you to help your son pay for medical school? Even doctors do not have an easy time paying off their medical school debt.
Which school would be best for “plan B” if your son does not end up going to medical school? The very large majority of students who start university thinking “premed” end up doing something else.
Which one would be the best fit, and where would your son be happiest?
It sounds like you have visited all of these, which is good and might help with the decision. Personally I would tend to lean towards staying in-state if everything else is equal. On the one hand this might minimize travel. If something goes wrong then help will be nearby. If a student takes an extra year (eg, to get a master’s, or for a double major, or for a late change in career plans) then you will still be in-state.