I tend to be a fairly consistent 120 nights a year hotel stayer ,that said and as crazy as it may seem I have never really paid any attention to the loyalty programs , I have Hilton Diamond ,Hotels.com Gold and by default Marriott gold through UA FF. though I rarely stay in Marriott's, no particular cause. Given the merger of programs is it time to flip to Marriott ??, I don't feel any huge benefit of Hilton Diamond , Hotels is ok for the flexibility if you are off the beaten track ,I am not emotionally attached to either.. My life is currently 80% US 20% INTL, that can change fairly quickly but that would be my prediction for the next couple of years.
Any wisdom ??

While I agree it's worth looking into, if OP is able to move even 50% of travel to Marriott, Platinum or higher will be attained.

OP: I would probably wait a bit to make a decision. The merger is creating all sorts of integration issues within Marriott right now. Furthermore, they've announced a new award chart but haven't yet announced more than a handful of category assignments, so it's hard to know exactly what your points will buy just yet.

Having said that, the single most important facet of a hotel loyalty program is whether or not they have properties in the places you go (and want to go, for award redemptions). Marriott Rewards might be a great program but still a bad fit for you if the nearest Marriott is 50 miles from the locations you're most likely to go.