I want to work in either health promotion or business (or apply both), the careers at my school had said swinburne is the place for health but I'm still not 100% sure
I would scrap Arts at ACU if you don't have an interest in it.
I'm not all that knowledgable about either courses, although I used to know someone who worked at La Trobe, which is supposedly quite good for Health Science. It might be worthwhile having a look at the courses at Deakin and Swinburne, and see which subjects you'll be studying and, which one appeals most to you. This was definitely a deciding factor for me when I was choosing my preferences.
Maybe have a play around on QILT, and see what you think? I'll leave a link here:
https://www.qilt.edu.au/Sorry I can't be of more help. Hopefully someone with a bit more knowledge of HealthSci can come along and offer some advice.