Hilton Diamond is far from worthless in my opinion. I certainly value it more then my Marriott platinum
but these are YMMV situations for sure.
In Ops shoes I would go for the Marriott status for sure. You can start with a taste of platinum challenge to get status up front.
Also at 75 night you can choose a free night bonus too
If Hyatt is a option for you I would look there before Marriott.
Just my few cents worth of advice