#1. top MBA is all fluff. you don't really develop your intellect, or really gain any meaningful skills. With law school you sharpen your analytical sense so there is more personal development.
I'm pretty sure that not all elite MBAs courses are fluff. While some topics like management tend to be fluff, if you're interested in the quantitative side, it becomes much less fluff. Many top B-Schools like Haas, MIT, and Wharton have departments or courses in financial engineering, statistics, operations research, and actuarial science.
Now, is JD fluff? One thing that's interesting about law academia is that lots of law professors don't have JDs or LLBs. If you look at Yale's faculty, there are lots of professors with just PhDs in Econ (example: A. K. Klevorick), or even MDs. Law professors with only Econ PhD or History PhDs are in fact very common at all schools. But you'd be surprised that there are those with even more remote degrees, such as well-known law and econ professor David Friedman who's a law professor with a PhD in Physics. So while a JD is more substantive than an MBA, law isn't rocket science that you can't learn on your own.
Third, fluff can be good in that it's not as stressful. Law school is generally not only stressful, but creates an overly competitive environment among students that's rather toxic.
I'm en route for a JD, but if I had a lot of work experience and could get into a Top MBA, I think I would've taken the MBA route.