I usually give the title to whoever can carry a division and whoever needs the popularity for it.
I gave Shinsuke Nakamura the WWE World Championship and he went from a great wrestler with no pop, to one of my Most Valuable Players. Same with Strowman. Meanwhile I gave Asuka the Smackdown Women's Championship and my Smackdown Women's division went from averaging 40s-50s to 60s in less than a year.
But sometimes I give the title to people that I just want to get over, like Tyler Breeze, Ruby Riott, and Karl Anderson and Luke Gallows. While I have them as champions I make sure to put them with people who I know will put on a decent match with them.