Pay is similar enough among different residency programs that it should really be a non issue. Sure it's a factor, as is CME money, book funds, etc. But an extra two thousand bucks won't change your lifestyle much. Call schedule is also not as big of an issue as some make it out to be. Sure it matters, but the eighty hour work week applies regardless of where you are. Also, if you opt for a really cush call schedule, you MAY miss out on important parts of your training. Reputation is tremendously tough to evaluate.
If you know somethings about your future desired practice, it will help tremendously. Location is tremendously important. A very high number of residents stay in the area of residency training. Networking makes it much easier to find a job/practice opportunity. Several residencies recieve funding based on how many residents stay in the state/area and you may be lead in that direction (my residency would only post jobs within the state). Do you plan on seeing lots of kids? Do you want practice in the hospital? Do you want to do scopes of other procedures? If so call and ask very specific questions. Do not ask, "can I get scopes at your program?" Ask, "How many of the residents who graduated in the last few years are performing endoscopy?" If you want to deliver, find out how many FM attendings are actively practicing obstetrics.