LLM,which is better?
I am interested in coporate law, and hope to find a job in big law firm

if i were you, i will choose BU.

though both are ranked almost equal; one is still in a better company in BU - being closer to Harvard, Yale as also New York and DC

I have similar problem though my concern in GULC/BU/Duke.. but BU has good program in corporate finance law especially the Intership program since it seemingly gives you advantage of being a step ahead in feeling the real work despite allowing a minimum of 10 hrs only I think. Moreover, there are more potential local and international contacts to be made in Boston.

I wouldn't choose BU over Duke. Incidentally I can say that both graduate office people there are extremely nice and informative.