there are quite a few hospitals in the nslij system...but if ur referring to either north shore or LIJ....they are actually both university hospitals ...north shore is the better hospital....however both places have a high amount of private patients....but i guess north shore wud give you better training after 3 years....the ancilliary services are excellent there....personally i wud still pick cornell over nslij
FWIW, both NSUH and LIJ are academic in name and fantasy only. Sure, NSUH has an academic affiliation w/ NYU and LIJ w/ AECOM, but (for better and worse) they are community programs. Their "academic" credentials come from having med students from those schools rotate through the hospitals and the staff get essentially honorific academic credentials. But don't kid yourself...you won't be doing a bunch of rotations at Montefiore (thank Buddha) if you're a resident at LIJ (or NYU if you go to NSUH).
They are both pretty good community programs and if what you want to do is community primary care/hospitalist stuff, either would be a good place to be. They're fairly benign, they pay well and have a decent spread of pathology. If you have any deisre to do a fellowship (although I had a bunch of friends @ NSUH and LIJ match into fellowships...mostly community) or have an academic career then Cornell is the way to go...otherwise either NSUH or LIJ would be fine (NSUH has better facilities, LIJ pays better).