I am going to start out with three assumptions: (1) At the end of graduate school, you want a tenure-track job, (2) While there are certain ones you would prefer, most jobs out there would be good ones, and (3) You want to do this without running up huge amounts of debt if possible.
If you were in any other field, I would suggest the MSU option. You would find a job with a degree from a good second-tier school (MSU is a top 20-40 school in most fields and subfields with some obvious areas where you can argue for a higher ranking), the cost of living is inexpensive compared to large urban centers and coming in with funding is a huge plus (it is much easier to keep funding than to get it after you start in most programs).
However the political theory market is brutal. If you aren't in one of about 10-15 programs, you have little chance of getting a tenure-track job. It isn't fair but that is a fact of life. Stranger things do happen, but you will have a very difficult task finding a job with an MSU degree with a focus in political theory.
If you could see yourself teaching in any other subfield, my advice is the MSU option is the safer course. The Chicago option is a gamble that will cost you ten of thousands of dollars for something that may or may never lead to a placement in one of those top 10-15 doctoral programs. I think you need to ask yourself "Would I be miserable the rest of my life if I never took that gamble? Is political theory that important to me?" If it is though, Chicago may be the better choice.