RB Kitaj might be interesting because he was an American painter who did it the opposite way, he lived in England for many years and then went back to America later in life, and David Hockney is living back in England now.
Kitaj curated an exhibition in the 1970s of artists like Hockney who were working in various representational styles against the avant-garde trend and they were known as the 'School of London', Francis Bacon, Lucian Freud and Frank Auerbach were some of the other most influential painters among them.
You have to compare David Hockney with someone equally innovative and important, not a commercial lightweight like Kincade or Kahn, and preferably who was also doing representational art around the same time but developing its expressiveness in different ways.
Maggi Hambling could be interesting as well to compare, she has done portraits as effective as Hockney's but in different ways, and recently a series of sea paintings - rather than his pools.
