Tons of lists rank the B-schools. As a sample, here is a widely cited list for undergraduate B-schools.
Best Undergraduate Business Schools 2014
And here is one for MBA programs:
The Best Business Schools List - Forbes
There are other lists out there too, but you can start with these. Of course the problem isn't really knowing which is best. The usual suspects are almost always the same -- Wharton, Kellogg, Harvard, Stanford, Columbia, Ross, etc etc. The problem is getting into one of the best ones. As you can imagine, competition for spots at the top schools is ferocious.