Re: Finance/commerce (accounting) or Law/commerce (accounting), which has more 'scope
If your focus is on whether your studies will be stressful, in all honesty, law probably isn't for you (assuming you are vying for an actual law role). That being said employment opportunities in top law jobs as a graduate (or even an internship) are not easy and I think the top firms tend to be fighting for the same pool of best candidates.
IMO having the law degree isn't a bad thing to have on your CV and it will definitely give you credibility in more scenarios than you can imagine even if you don't work as a lawyer. Like many studies, it's not what you know but what it says about you and your reasoning/character/etc.
If I could do well in law (i.e. put up with the readings) then maybe I would have pursued it but I knew it wasn't ever going to be for me.