Hey congrats on your acceptance to SLU. I think it's really tough to compare these 2 schools, like many other NYMC vs. ____ decisions, it comes down to more than just the education in my opinion because they're probably similar.
As far as matchlists go, here's SLU's:
http://medschool.slu.edu/matchlist/index.phtml?page=matchlist_2006
and here's NYMC's:
http://nymc.edu/admit/Medical/info/Match2006.asp
Sometime's it's good to compare how many people matched into competitive specialties (although this will depend on several factors, e.g. what students actually wanted to specialize in) But it's a good start...
Neurosurgery: 4-NYMC, 0-SLU
Dermatology: 1-NYMC, 0-SLU
Ophtalmology: 4-NYMC, 3-SLU
Orthopedic Surgery: 8-NYMC, 4-SLU
Rad-Onc: 0-NYMC, 2-SLU
Anesthesiology: 23-NYMC, 9-SLU
So NYMC's got SLU beat in most of these... but it's tough to say that that actually makes it a better program. It also depends on class size (I'm pretty sure NYMC's is bigger) and what people were actually more interested in.
Where did you feel most comfortable? What kind of city are you looking for? Are you more of a southern hospitality type person??