Dude, dont be retarded. Columbia all day. It's a better school with a superior reputation, especially in NY. Your investing way to much time and money to not go to the best school you can. At either school all you'll do is study your ass off, so dont worry about the environment to much. NY is 100000^100000 times better to live in than Ann Arbor. Choosing UMICH over Columbia is something that you'll regret for a long time. Also, do not let cost be your deciding factor. Loan terms are very favorable and law students get money really cheap, the difference in price will amount to a couple hundred dollars a month on you student loans.
Think about it. Columbia is the obvious choice here