For myself I just wanted the whole thing off which did turn out to be the right decision as with pathology it was in the sentinel node as well and most likely the second op they would have done mastectomy along with the full node clearance they did anyway. I am not a big breasted lady at all and the cancer breast was the big one so I figured just get rid of the whole thing.
If I was a big breasted lady and quite feminine ( I am more tomboy) I probably would have tried the lumpectomy side of things to preserve as much breast as possible. In the end it is your decision. Not your partners, not your family's, just yours.