Milestones are nice, but they don't really move the needle for me.
I'm now at 114 Marriott nights vs. 34 Hyatt, and yet I still keep booking primarily Marriott because I like the properties better in the places to which I'm currently traveling (mostly OC, West LA, and SF/Oakland).
I'll make my 60 Hyatt this year, the value of Globalist is still very much worth it. But Milestones won't incent me to book away from a Marriott property that I like better.