Well, I might not drop the filler if I end up with good ranks in that subject.
Biology vs Chemistry? What do you like more?
I heard Modern History is pretty interesting?
Well I encourage you to not go in with a preconceived filler, do your best in them all and then drop the worst for yr 12.
Biology vs Chemistry=Well for me Bio is very easy, I can get good marks in it, probably because I have a good memory. Some of the the prelim content is very fry about plants but some of it is interesting (like evolution of aussie megafauna). One good thing about bio, is the dot points follow in an easy to follow order and are super clear.
Chemistry though, is my most interesting subject. But I find atoms fascinating personally. However, it is much more challenging than bio. There is a lot more content and skills needed.
But yeah probably not the best person to ask, as Chem/Bio are my fav two subjects. However, I will tell you I thought Bio was going to be my dropping subject, but when I got in, it was far more interesting than I expected. They both have their merits-personally just up to what scientifically is more interesting for you. But I suppose Chem probably, it is a recommended study for a few uni courses where Bio is often not.
Modern History- I'd say it's interesting level is really dependent on what topics your school does/what teacher you have. You see I even managed to enjoy SC History cause I had an amazing teacher-unfortunately that teachers takes the other Modern class. So I recommend if you're interested, seeing what topics your school does-as any historian has their own interest field. It's a pretty good subject though. I'm glad I picked Modern over Ancient if you're wondering that.
And just as an aside, Engineering Studies could be a good complement seeing the maths/physics you are doing.