well depends on what subject you will be working on?
U-M is much stronger in micro/nano fabrication ( one of the best actually), whereas CMU could be more beneficial if you are going to work more computer related research.
Hi,
I am currently at A&M, and I would definitely suggest you to come here. It's waaay bigger and richer than the two other institutions you mentioned. It has pretty good neuroscience program too. And the life is cheapest by far. Probably cheapest in the whole nation!!!