I've had the SPG Amex card a long time, even though for years my only spend on it was for my occasional stays at SPG hotels (Hyatt & Fairmont were my main hotel loyalty programs, but I also stayed at independent hotels and specific hotels in other chains that suited my purposes better). I'd accumulated a fair stash of miles usable in OneWorld & Star, which met my needs for the occasional F award to Europe, Southeast Asia or Japan, so was not particularly interested in airline transfers. But I did want to take a shower in the sky, and was planning to get to India sooner rather than later, so when AS overnight exponentially increased the miles needed for an EK F award, I found myself in real need of JL miles; the SPG Amex became my card of choice for non-bonus spend. (I did go to India and get a shower on the way home, as well as en route to and from the Maldives. While JL is a lot less attractive for EK F awards now, I nevertheless did another couple of transfers recently so that I can have one more roundtrip to that region.) But that party is coming to an end on August 1.
Accor has killed off the Fairmont program, and 60 nights at Hyatts does not fit my travel patterns, so I ended up at SPG. I've enjoyed it so far, am a bit skeptical about how things will be down the road, but intend to keep at it and see how things develop, so I want to keep one card for use at the hotels (but don't see a need for two). I picked up the old Marriott Rewards card a while back when Chase was about to impose its 5/24 rule for some of its co-branded cards. I used it for Marriott stays until they started giving bonus points for using the SPG Amex, too, but now it sits in my drawer. As between the MR and the SPG cards, I favor the Marriott, because of the potential to acquire extra nights' credit for spend (just in case I need it), and because a lot of my time (and money) is spent outside the US, and Visa's FOREX rates tend to be more favorable than Amex's. Next year I'll consider one of the new cards, but if the old MR card retains the extra nights for $3K spend feature, I'll probably just stay with that. But it will be used for hotel stays and little else.
For non-bonus spend after August 1, I still need to put some spend on my AAviator card (I don't love getting more AA miles, but I do love getting upgraded, so want to keep my EQDs up as well as keep EXP for another year) and then I think I'll look at Barclay. I am a big fan of the CSR, but travel so much that I don't feel I need to use it for non-bonus categories.