I think that Kennedy was a very good president, but I think that LBJ was miles ahead of Kennedy when it came to domestic issues. Johnson's civil rights legacy to me should far outweigh the Vietnam War weight.
Absolutely--this is what I was going to say. LBJ was one of the best presidents ever in domestic affairs. It's extremely difficult to give him an overall ranking, given that Vietnam was such a disaster. Nevertheless, if someone forced me to at gunpoint I would rank him a "near great" president. The highest I would go with JFK would be "very good."