I am currently Hhonors Diamond (only takes 30 stays) but am thinking of switching to Marriott. I have SPG/Marriott Gold through AMEX Plat. I can probably make it to 35 nights next year in order to make Marriott Plat in 2020, if I get one of the 15 night credit cards.
So, it seems that a reasonable strategy is:
Now-July (stay in Hilton, where my Diamond is worth more than Marriott Gold)
August-December (stay wherever, as I'll have Marriott Plat)
2019 Suffer through a year of Marriott Gold in order to make it to Plat late 2019/2020
Unless the devaluation hits hard, it just seems that 15 marriott points per $ is worth much more than 20 Honors points per $. The Honors points are worth 8 cents, while 15 Marriott points gets me 6.25 miles, or about 10 cents of value at hotels (unless there's devaluation).
Am I off on my analysis?