Hello there,
That is true. But neither is BU! They are in fact on similar ranking levels, and both of these schools have good names. Yes, for sure these schools are less good that S16, and if you can get into an S16 then that would be much better! A lot will depend on you and your profile.
Well both BC and BU are considered quite good schools in the US (and are ranked at similar levels). And it’s a good Tier 2 MBA. You should of course consider 3-5 other schools to make your application strategy too.