Best New York cancer centers?

For the past two months my mom has been seeing doctors at the NYU Langone Center. The hospital was recommended to her by way of a friend who has an oncologist friend, and this was the oncologist friend's recommendation. She really likes her doctors, they have a great bedside manner (I've witnessed that on visits with her myself) and they seem to really know what they're doing. Of course, this is coming from my parents and I, who've never had reason to study cancer in depth before. And my mom is very susceptible to a caring, sympathetic voice and demeanor.

She is so weak and in such pain that I've hesitated to suggest checking out another doctor before now. (She's taking oxycodone and Fentanyl patches, but when she gets the urge to go to the bathroom, nothing helps.) At stage 4, and with the kinds of mets she has, we're certainly not hoping for a cure, and she's been given 1-2 years tops (she's 57 years old). She will be getting a colostomy soon, no appointment yet but they're doing the cat scan today to see the progression of her tumors after chemo and radiation - oh dear god I hope she will be able to get the surgery this week - and after she has been able to settle in with that and is hopefully in less pain, I'm thinking of urging her to try making an appointment at Sloan Kettering or NY Presbyterian. I'm not sure what I'm hoping for - doctors who will give her more than one year? Better pain management even though, realistically, there was nothing else that could be done at this point short of inducing a stupor? Even a second opinion on what the right next treatment for her would be at this point, whether continuing the same chemo regimen or trying another?

My big problem is I just don't know how to judge hospitals for cancer care. I feel like NYU, Columbia-Cornell and Sloan Kettering are NYC's big three, but at her advanced stage, which would be the best? She got the recommendation of a specific onc at NYU, but her tumors were so progressed he couldn't do anything for her anyway, and had to refer her to others in the Center. What else can/should we do???