Richard Nixon ran unopposed in the California primary in 1960 and did not enter that primary in 1968.
One contest that featured three strong candidates was the California primary of 1928, which Hoover won by 49 percent. Although he didn't score that big a win, Cruz's victory over three strong opponents still is impressive.
Your #39 posting here is informative. Thank you. It was a pleasure to read a posting with factual data rather than the mudslinging being done on most threads by many.