There are lots of merits to an older, well established profs. Younger profs are also more ambitiious though to make a name for themselves, tenure, etc. Tristan Lambert worked in David MacMillan's group when he was relativitly unknown as an assistant professor at Berkeley. It probably a mix of name value and school reputation, but also, I think its largely the grad student who shapes their own future.
But like YaBoyAR did, it would be a good idea to contact older profs to see if they are still accepting grad students. Though many group pages will say if they are accepting or not.
I never bothered to contact any of my POIs before my applications. I dug through the group pages and recently published work of those profs I was interested in. I made mention of my POIs and some of their projects I liked in my SOP. If you get accepted you will most likely visit and meet them in person.