Over the past few years, I have been looking pretty intensely at the different b-school programs, and the BW rankings were kind of my jumping-off point. I soon became confused by the divergence among the different rankings, especially FT and WSJ.
Over time, I came to view an individual ranking, or at least a school's spot on a particular ranking, as essentially meaningless. When we look at the rankings, we usually want someone to tell us, "Which school is the best?" or "Is this school better than this other school?". And ultimately, these questions have no answer.
My view is that the rankings are useful in summary, to get a general overview of the b-school landscape. Taken together, the rankings give you a good intuitive feeling for which schools populate each tier. Considering how different BW's ranking system is from, say, WJS's methods, you can be confident that any school near the top of both is widely respected. You will not, however, be able to definitively claim that "Kellog is better than Haas". Those statements have much more to do with a particular student's interests and background than the opinion of the community-at-large.
Frankly, I appreciate the specialty rankings much more than the overall ones. For example, if you are sure you want to pursue a career in the nonprofit world, look here:http://grad-schools.usnews.rankingsandr ... non_profit
The specialty rankings distill somewhat this obscure knowledge into an accessible reference.
In summary: don't waste your time ranking the rankings. If you're really serious about graduate school, read them all and get a gut feeling for which schools support your goals. Or, better yet, discuss your interests with someone who already understands the wide world of business schools.