My money would be on the older person sticking around longer. It's very uncommon for anybody to work at the same company for decades any more, but older people

My money would be on the older person sticking around longer. It's very uncommon for anybody to work at the same company for decades any more, but older people tend to have children, mortgages, and other commitments that keep them from jumping around too much. Besides that, younger people will require larger raises to keep around because the difference between 1 year of experience and 3 years of experience on a resume is significant, while 30 years vs 32 years isn't. The older person will ask for a higher initial salary, though. I'm also skeptical the 25 year old and the 55 year old will have the same skill level, assuming the 55 year old has been in the industry for any significant amount of time. Edit: I didn't see "junior" in your comment when I wrote my reply.