I use both Hilton and Marriott and to me, Marriott points are definitely more valuable, but Hilton points are much easier to earn...especially if you get points from credit card spending. As a rough estimate, I value Marriott points at about 1c-1.5c per point and Hilton points about .33c-.5c per point, but I really look more at how much credit card spending it costs me to get a free room. In your example for the Marriott, it would cost me $25,000 of regular spending or $12,500 of restaurant spending (2 points per dollar) for the 25,000 point room. Since I only use my Marriott card for restaurant spending, let's say $12,500. With Hilton for 40,000 points, I would use $6667 of spending (6 points per dollar for grocery and various other bills). So to me, the Marriott points are about twice as valuable as the Hilton points in this case. So if the quality and other features of the hotels are similar, I would say the Hilton for 40k points is the better deal.