I haven't been on this forum for very long, but I'd like to take a crack at this question. I just finished this whole match process, and what I looked for in a program was:
1. a program that let you spend a day to preview slides (gotta have time to read)
2. a program that is centered at one hospital (I don't like learning different systems)
3. decent hours (because I just don't think it's necessary to work your butt off into the wee hours of the night in path like it might be in the clinical specialties). This includes free weekends.
4. good track record of graduates into both private and academic practice. Here, I wanted a program to give me a list of jobs that recent grads got.
5. >20,000 surgicals a year (this is perhaps arbitrary on my part)
6. affordable urban center (gotta have something to do with all my free time in path!)
7. nice folks on the interview day, particularly a residency group that seemed not only happy, but that seemed like a group of people I wouldn't mind hanging out with.
These are the things I looked for, but then again, I may end up regretting my choice after I've started my residency.