It is good that you don't have to worry so much about the prerequisites, and even then, you could always do either as a foundation first year unit or bridging course at uni, if you suddenly decided you wanted to be something that required bio, for example.
Your school may not let you drop both, but you could try. Otherwise I think in your case it is more important to pick the one you think you like the best. Doing things you like can actually help guide you to a career you like, but at the end of the day after uni no one is going to look back at what you did in VCE.
Commerce etc would have legal stuff in it but I can't really speak for that.
It might also come down to balance. What are your other subjects? Some people like to say have everything in a similar area, others like a bit of a mix so their brain isn't always focussed on numbers, say, or always focussed on essays. It might be that as you can't ditch English, you might ditch legal, which has a lot of reading/writing, but then is applicable to commerce and business.