Buffalo is a very good program- actually a "hidden gem" type program. I rotated as a medical student, and I have some good friends up there in the program. It is huge, with several different hospitals. All the divisions are pretty strong, and rotations include a stand alone children's hospital and NCI cancer center. I rotated on trauma surgery which is a very high volume service with a lot of both penetrating and blunt trauma. I also rotated on vascular at a smaller hospital- lots of good cases including AAAs, carotids, thoracic outlet, distal bypasses and a ton of endovascular cases done by vascular not IR. The attendings are great, but a drawback is the relative lack of academic attendings with international recognition. Dr. Dayton is the (relatively new) chairman, and a great addition to the program. I have a feeling that Dr. Dayton will seriously elevate the quality of the program from an academic standpoint. The drawback, of course is the weather. Buffalo is actually a neat city, but winter just seems to go on forever.
That being said, Rochester stands alone in upstate/western NY. In addition to being an excellent clinical center, Rochester has a very strong academic flavor, with a lot of good research. The faculty is very well known from an academic standpoint, and the program should really be considered a top tier program on the national level. The facilities are beautiful/modern with ample ancillary services. The drawback, again, is the area. Rochester is smaller than Buffalo. It has a more "white collar" feel, and compared to Buffalo probably a little bit less to do outside the hospital.
I can't really accurately speak of the "malignancy" of either program, but I didn't get the feeling that either program was malignant.
I do have to say that despite its (unsubstantiated) reputation for being one of the worst places to live, western NY is very affordable, family friendly, with plenty of culture, great food, etc. $500/month can get you a killer apartment, and buying is easy and affordable. I live in a small NYC studio for about 1000/month- I'd have a 3 bedroom apartment with fireplace, garage, several mistresses, full time masseuse, and BMW if I were still in Buffalo! If you can tolerate the cold WNY is actually a great place to live. A good number of "downstate/NYC" friends during medical school decided to stay in either Buffalo or Rochester for residency.
Anyway, I hope this helps and feel free to PM me if you have specific questions.