Michelle from what you've said, I would personally go with biology. This is only because you already find genetics interesting, which is a big topic in year 11 (+ a bit in year 12). Ultimately, you want to pick a subject that you're interested in. No VCE subjects are "easy". It depends on so many factors, and enjoyment is a huge one. Biology also doesn't just go look at cells, but it explores things like the immune system, enzymes, genetic modification and gene study techniques, stem cells and development, environmental biology, evolution, how species form (which ties in with genetics), regulating cells in the body to prevent things like cancer, immunotherapy and other medical treatments, etc. I will say, year 12 bio is better than year 11, but that is my personal opinion haha (I feel like the topics are more interesting and applicable, since you have the foundations from year 11/likely do). Biology also involves memorisation too, although of course understanding the content is key. HHD is a really well loved subject, but I've heard it can be very challenging when it comes to answering questions to get the marks(i.e. you can know something, but it doesn't mean you can apply it properly -> Important in bio, but I've heard it's more difficult in HHD) and very content heavy (same for bio though). Basically, just don't assume any subject is "easy" because they all have pros and cons, and plenty of challenges.
Of course, you have to make the final call. Ultimately, choose what excited you more in terms of the content. Read through the study design and maybe ask a few older students about it.
The only other thing to consider is what you want to maybe do after school, since this could impact which subject you'll want to pick.
P.s. Just letting you known that I'm probably a lil bit biased because I studied bio in VCE and study it at uni haha.