Go for legal if you enjoy memorising large chunks of info and regurgitating it all on exam day

The final exam is a massive handwriting speed contest, no joke!
VCE Economics will help you HEAPS if you do a Commerce degree at Monash. I regret not taking economics instead of chemistry. Around 1-2 of first year subjects are economics-related in B.Comm, I wish I'd realised this earlier! It's useful.
Legal studies will help you in the first 7-8 weeks of Law, LOL! Especially with 'Introduction to Legal Reasoning' unit, you'll find that if you've done legal studies, you'll understand and pickup alot faster than those who haven't. If you do legal then go into a law degree, you'll already have a really, really solid understanding of the whole legal system and a bit of law when others start at zero again.
However having said that, legal doesn't help with the real full-on law subjects like Contracts..

IN OTHER WORDS:
Do Eco in you're planning to do Commerce
Do Legal Studies if you're planning to do Law.
Both subjects are important!

But yeah I loved legal <3