I think you need to decide why you choose Hilton or Marriott in the first place.

Is it because one hotel is better / offers more in terms of perks or comforts? I think in this case they are even. What I don't know is what Hilton offers you for your 30 nights a year. How are you treated? Is this a premiere level at Hilton?

Is it because one of these hotels has more choices in the cities you travel to? This would be at the top of my list, and only you can answer this.

Is it because of the rewards program? From my understanding, Marriott's program is one of the better ones in the industry. They have many hotels in prime locations which offer excellent vacation opportunities. To me, this is very important as well and is one reason I choose Marriott.