Almost everyone is going to tell you: Going to a school of public health offers you more resources than going to a program of public health within a school of medicne.
That being said, both the programs and schools of public health are held to the same academic standards in order to be accredited, and only schools of public health are ranked, not programs, so it will be hard for you to find any rankings (if you're into that sort of thing) on programs.
That being said: I applied to Tufts dual degree program (MPH Global health/MS Nutritional Epi) and went to their open house. I did not apply or consider BU. I found Tufts to be a VERY intimate program, where the school of nutrition is split between policy students and science students - the incoming class of science students is expected to be around 14. They definitely gave the impression at open house that you'll have an advisor to work closely with you, and who only advises you and maybe another student - not dozens of students.
I've heard different view points on the dual degree idea, some think having the M.S. in Nutrition in addition to the MPH can really strengthen your degree, others believe nutrition is more of icing on the cake, and that it would be more important to hone a public health skillset.
I did go to Visit Emory (which, btw, did not seem to have much emphasis on nutrition.) and met with a guy who had gone to BU for his MPH and his wife was going to Emory for her MPH. The guy had felt he left BU without very many skills, and mostly thought about public health, critiqued it, analyzed it, but lacked the skills to work within the field. He also did not feel their career center was terribly good.
I don't know what Tufts has in terms of connections with companies or agencies (aside from the USDA Human Nutrition research center on aging.) or what their career center can offer in terms of working after the degree.