This is a good question - you to talk to helg - he had a similar decision last year (and chose Booth). PM him, or maybe I can put you in touch directly (im not sure he logs on anymore, does he?)
For what its worth here's my totally 100% honest, mostly factual and only sort of biased reply. First, let me state the obvious: I am of course ignoring all other variables -- eg, I assume you actually LIKE both schools, have visited them, have no other major reservations, etc.
1. Recognize that $100,000 is a tremendous sum of cash and that the choice of going to Chicago (which has many positives certainly) will likely put you in debt for a number of years. Don't just discount that so easily.
2. Further, recognize that getting a job in consulting is going to be 50% prep and 50% luck - did you get a case you liked? Something you knew something about or something truly random? Was the interviewer tired or frustrated? How were you on that day? Did you two 'click' and get along or did you two not connect? Will you have a conflict with a 2nd round and have to pick between going to one 2nd round and another? To what extent does any of this change whether you are at Chicago or Ross? (I'd say none)
3. Getting a job at MBB is the same as 2, but even more variability and substantially worse odds. You have two person first rounds, usually three person second rounds - what are the odds you nail all 5 of those case interviews? What are the odds someone will connect with you 5 times? What are the odds you perform in the top 20% consistently? To what extent does any of this change whether you are at Chicago or Ross? (I'd say none)
4. I can't tell you how many interviews for those three occur at Ross but at Chicago its about 100 interviews for each one (total of 300 interviews), but were talking about ~20 or so people going to each of those firms. That along says your odds of getting MBB are about 1 in 5. If you consider that more than 100 people apply to each, its lower (although if you are dedicated you can pretty much ensure an interview). To what extent does any of this meaningfully change whether you are at Chicago or Ross? Are Ross' odds 1 in 10 or are they 1 in 6? (I'd say none)
5. Don't underestimate your competition. People are smart. To what extent does any of this change whether you are at Chicago or Ross? (I'd say none, realistically people are just as smart at both schools.)
So, hows that boil out for me?
Without sounding offensive - its no reflection on you in anyway: you probably wont end up at MBB at either school. Realistically - everyone thinks they will get MBB, but the truth is maybe 20% do. There's heavy competition for those jobs, and the pure statistics and sheer variability in things over which you have no control (how the interviewer feels, whether or not you get a good case, whether or not you two connect) are totally independent of whether you end up at either school. (Now, there might be a difference in the odds of getting the interview in the first place at one school vs the other - that I dont know. You'll have to do some research there). If you can accept that MBB is going to take as much skill as LUCK -- and no amount of studying or prep can eliminate that risk -- and no school can eliminate that risk --- then I can think of few reasons not to accept Ross (assuming of course you consider everything else on par). So on balance, if I'm totally honest, I'd say you should choose Ross.
Now, it wouldn't be fair to say that without the flipside of the coin.... and I'm happy to make the case for Chicago too - there are a lot of great reasons to come here as well and if im happy to chew you ear off about it sometime. I'd urge you to reach out to helg too.