I would take Questrom because it is far more selective, and as a result, it will be viewed far higher by employers, both for actual jobs and for internships. However, the two schools are completely different. I love both, but walking around the incredibly big campus of BU is quite the pain. If you know you’re going to do well at Bentley (like 4.0 level) then you can pass on Questrom, because personally, if I were to live at Bentley, it’s just far more beautiful and pleasant to look at.
It’s a cliche bit of advice, but take a tour and see which one tugs your heart. Your gut feeling will definitely help.