My opinions are that both EL and Detroit have plusses, whereas Macomb doesn't have too much going for it. Here's why I think that:
EL: Main campus. I believe this is where the classes are all taught (correct me if I'm wrong, but I think lectures are streamed to Detroit and Macomb from EL). College life in a nice city -- you get the full MSU experience here.
Detroit: Fantastic and close clinical partnerships. Really gives you a good setup for making connections at DMC.
Macomb: Affordable housing. Otherwise...??? I personally can't see any reason to choose Macomb over the other two locations without some outside reason. Perhaps growing up in metro-Detroit has made me a little resistant to living there for another few years. If you want to be away from a big school town, have affordable housing and/or maybe have family in the area, then it's a fine place to choose. I just feel like you're slightly compromising on the experience and/or networking opportunities.
Those were some of the thoughts that went into my decision to chose EL... so of course I'm a bit biased.