Most of what I'm going to say is hearsay, but I'll just say it anyway in case it helps.
A friend of mine is in the same position as you, ph04. She'll probably miss out on UNSW if the cutoff rises by a fraction. Her preferences as far as I'm aware are:
1. Commerce/Arts @ UNSW (the cutoff is the same for a single BCom)
2. Business @ UTS
3. Economics/Arts @ UNSW
4. Commerce @ USyd
As you can probably see, she's considering UTS over USyd. I'm considering Com/Law myself and I haven't heard anything negative about USyd's Commerce degree at all. The new economics and business building looks great too, so bonus points for that.
If social activities is a big criteria on your list then I would suggest USyd - purely because I've heard alot of good things about this. ComSoc runs some balls and actitivies... it all sounds really fun.
Contrary to popular belief I don't think USyd's Commerce department is in any way less 'industry tailored'. If you're hoping to be recruited to investment banks and the like, USyd seems to have substantial industry contact. This is a huge factor since the majority of vacant positions are not advertised and industry contact is one of the most valuable assets especially when you're fresh out of uni.
If you're having trouble choosing between the two, I would suggest nitpicking a little and going on less important differences. (ie. USyd has nice grass and a shiny new commerce building!) But keep in mind that it's best to choose what feels right for you rather than on someone else's convincing argument. That's basically all we highschoolers can go on - what FEELS right.