I've been to Victor's and a number of others in Little Italy (Medford). The best chicken parm sub hands-down is Bob's on Main Street in Medford. Fresh chicken, sesame seed bun (seeds a must), fresh provelone and great sauce. Seems so simple, but few do it well. None as good as Bob's.
I have never been disappointed with the Chick Parm at Tommy Floramo's in Chelsea. A full breast of chicken, lightly seasoned and breaded, pounded thin with sauce and a side of pasta. Very inexpensive and very filling.