I have not really analyzed the waitlist admit majors since the schools do not officially list the majors pulled from the waitlist, only what students post on the social media sites, but in general the College of Engineering usually has the least amount of admits and the College of L&S the most since the majority of majors are found in L&S.
You are welcome to review previous waitlist threads to see if there is a pattern. You have to remember each year can vary so it all comes down to what are UC Davis’s priority in filling their Freshman class.