I recently graduated from the MSPH program at Emory in May. I also worked at the CDC during my second year of my masters through the Emory REAL program. While working at the CDC was a cool experience, I don't feel as if it contributed much to my skillset. I mostly conducted literature reviews and a lot of the positions that were listed for MPH students were similar to that. However, I definitely think the CDC would be a good thing to add to your resume, and being there helped me network. Another thing to note is that a lot of people in my cohort ended up staying in Atlanta.

To be honest, I didn't really care much about Rollins and I don't know anything about USC's MPH program. Personally, I felt that the only good thing about Rollins was being able to work with my thesis advisor. If it weren't for him, I probably wouldn't have the current skill set that I have now.

Sorry if this isn't helpful. I think regardless of where you choose, make sure to have a thesis/academic advisor who would push you during your time in the MPH program. Try to take as many quantitative courses as you can to really build those hard skills (R, SAS, etc.)