I go to Hopkins. Feel free to ask me anything. In general, resources will depend on your interests (e.g. in my school we have a ton of people working on cardiovascular, HIV, and kidney outcomes because so many professors are involved with the ARIC, MACS/WIHS, and CKID studies; in contrast, I have found that Columbia has more researchers who are looking at substance abuse.
FYI: I have not heard good things about Columbia's PhD program, but a) I'm obviously biased, considering that I'm in an environment where people are going to be prone to say things like that and b) I don't know if those criticisms hold true of their other programs. To try to prove that I'm not just being bitter, I have heard incredible things about the caliber of methodology education at Harvard and think they are almost definitely stronger in that area than we are.
They JUST sent out a round of PhD acceptances. I don't know if the committees are the same - probably not - but from what I can tell their admissions has been slightly behind everyone else (JHU sent out their PhD acceptances on the 14th, UNC was before that, Columbia was around now).