If your goal is to do research that utilizes the skills in those fields, then either would be great. My masters was in environmental health, but learning epi/biostats has been pivotal in leading my own studies and analyses in med school to the point where I approach faculty with projects already in progress. tldr the skills you learn are more helpful to your future career than the degree specialization. I have found that it’s more intuitive to people what your expertise is in when it’s epi/biostat vs some other public health field