John Lennon - talk about arrogant pricks. First he covers up Julian's birth because he was afraid the young girls wouldn't like him if they knew he had a kid. Then he cheats on Julian's mother with that cow Yoko Ono. Then his father wouldn't speak to him for years until May Pang (who Lennon was cheating on Yoko with) brought them back together to a degree in 1973. It wasn't until after Lennon was killed that Julian opened up about how verbally and emotionally abusive John was to him - he once told Julian that Julian came out of a whiskey bottle on a Saturday night.
Now you compare that to McCartney? The only person to really speak badly about McCartney was Heather Mills, whom everyone now regards was a phony golddigger a la Beth.