What is the cost difference? I would go to whatever is cheapest
Tufts is a more established school, so there are more opportunities you can take advantage of. However, the class size seems to take a negative toll on many students.
Here's an AMA I found on Tufts that might help you:
Tufts Ask Me Anything PM me if it's personal or you want help applying
forums.studentdoctor.net
Roseman is a fairly new school so there are less connections to build off of, but I have heard positive reviews about it from current students. It is also a P/F curriculum at 90%.