Bactracin Ointment or Neosporin Which is Best to Use on Nipple After Reduction, Free Nipple Graft?

Bacitracin or Neosporin (also called triple antibiotic, or polysporin)  ointment are similar. Neosporin contains Bacitracin, Neomycin and Polymyxin. For my patients I usually recommend Bacitracin as if you develop an allergy or sensitivity to one and the others are present on the skin you have a higher likelihood of also developing a sensitivity to those antibiotics as well. Both reduce the chance of an infection similarly in my experience.

Always  best to check with your own plastic surgeon about concerns after surgery.  Remember that he/she knows your situation best,  including the existence of any drug allergies.
Online consultants will not be able to provide you with meaningful advice.
Best wishes;  hopefully, you will be very pleased with the  long-term outcome of the breast reduction procedure.

Since you underwent a free nipple graft, you will want to use a cream that decreases the bacterial load but not interfere with wound healing.  I normally recommend stopping either one 7 days after the surgery and switch to a moisturizing cream or petroleum gauze.  I would check with your PS to see what his/her recommendations are.