I'm not sure what your choices are. If you are asking us Stanford / Harvard / Yale vs. HKU, well then, ummm, oops. If it is is University of Illinois, Penn State, William and Mary vs. HKU, well, that is a bit more difficult, but I think many would value a US education even in the second tier of schools. If it is Cal State Fresno, or Eastern Illinois, or East Carolina University vs. HKU, well then there you have a bit more of a choice.
One thing I think I should note, made more because of your comment / plan to get an MBA and thinking 6/8/10 years ahead to that already is that you should really take a step back and think six/eight/ten months ahead for the time being. There is a very real chance that you are going to HATE Hong Kong and be on the next plane out. There is also a chance you may LOVE Hong Kong and never want to leave.
But as you go through the next year, remember it doesn't have to be "this way" or "that way." You have a lot more freedom than you probably have considered. You could do a year at HKU and then transfer to a US school and get your degree from the US institution. Maybe if you do really well in HK you could get into a Yale or Stanford, or maybe you'll end up loving HK and never want to leave. Just don't think that "I have to do this for this long" and then "I have to do that" and then you'll be an entrepreneur. The opportunities come a heck of lot faster and from out of left field than that. You could have a dinner or a lunch with a couple of guys from HKUST wanting do to a website that goes IPO in a couple years. You never know. Or you could go back to the US and get a degree, do the standard banking/finance thing and then go for the MBA.
I think one thing you need to realize is that every day, every month, every year doesn't have to follow a plan. I am an entrepreneur, I've started two companies (one dead, one with a high valuation) and I can tell you somedays I have no idea what the next hour will bring. I started one company with $36 in the bank, made $12,000 in Vegas the next week, and then closed $1.5 million in VC funding six months later. That one fell apart. From the pieces of that I've built another that is functioning and employing several people around the world, doing something I (or anyone else) hadn't even thought of three years ago. Graduation date for your MBA is approximately 8 years from now. Make a list of things that didn't exist 8 years ago and you'd probably be shocked.
I guess my point is that you have a lot of choices. Don't think there is a 'bad decision' in this case. Looking at my kid on the floor I'm reminded that there are two ways to play with Legos--build exactly what see on the box cover, or build exactly whatever it is you want. Most entrepreneurs are the latter....
Good luck with your choice.