Well, do you enjoy French? And do you enjoy HHD? I find this the most useful in judging how you'll go, because the subjects you enjoy also tend to be the ones you're strong at.
In terms of medicine, HHD may be useful. But are you sure even if you drop French for HHD, you will get another English teacher? I understand that usually the English teacher you have for transition this year will be your teacher next year, but there is a possibility things might change. That saying, I do feel having a good English teacher will be massively advantageous for your study score and ATAR.
I also do agree with @Coolgalbornin03Lo about HHD being scaled down. But that saying, choosing a subject that scales down may not strongly affect your ATAR, since you could maybe have time to invest in your other subjects.
I'm not sure if this advice will help, so I'm sorry if my response isn't very clear. But I think it's important to go with what your heart thinks.