If ur intention is to work in finance after grad, the co-op program would be far more conducive as it'll reduce the burden of having to secure industry experience while studying. Tho I don't believe whichever degree you pursue will undermine ur chances of working in finance - they're both competitive programs
Personally I would go with Law and Comm at usyd. That law component would score big points. Ik a lot of my friends who are doing comm with the intention of inheriting businesses or stating some etc, but they double it with a law degree for the bonus credentials.