One thing that is left out of the equation (and the webflyer program comparison site that was linked) is the treatment of elites on priceline stays.

I am close to elite in both Marriott and Hyatt programs. From what I can tell so far, Hyatt provides far superior treatment to me on priceline stays (e.g. better rooms, club access) and sometimes even miles. Would be curious to hear how one is treated by the other programs.