Hey J_Rho

I haven't done Legal, Politics or Economics but I just wanted to pop over here and say that IMO, HHD is a pretty good introduction to Australia's healthcare system (e.g. Medicare, PBS, Private Health Insurance, etc.) #nobias

. You get to learn about the health status of Australia and health in a global context.
A lot of the content is applicable to everyday life (I'd say more so than Politics or Legal), and you can pick up the subject quite easily without Units 1 and 2.
There's a bit of rote learning of definitions in HHD, (e.g. the dimensions of health and wellbeing), and I'd say this is present in the other subjects you mention, to my limited knowledge.
I would also consider choosing based on which one you think you'll enjoy the most (based on the info you have) as you will enjoy studying for it more and it can guide your future career aspirations. The study designs of each subject, found on the
VCAA page, can give you a more specific insight as to what you will be studying. Even looking at past exams to see the types of questions or asking your Legal teacher or the HHD teacher(s) at your school could help.
You have Legal which will be the most directly related to law, so HHD could almost give you the best of both worlds? In saying this, Legal and Politics / Economics link in the subject matter through the different fields of law and the actual law making process.
Do you enjoy humanities subjects and are you willing to have one plus Legal in your study load?
Additionally, studying a subject through VSV is quite independent in nature compared to learning in the classroom (as Geoo has mentioned above). Could you imagine yourself undertaking a subject largely online?
Good luck with your decision and feel free to let us know what you end up choosing!
Hope it all goes well.