This seems like a key criterion right here. Maybe a two-tiered approach would be best?

Think about the SPG AMEX for higher-end stays, especially using cash&points. In the worst case, you can transfer to airline miles and it's still a great value.

Then think about some of the other cards for programs with a wider geographic reach and/or situations where AMEX is not accepted. Priority Club is great for "a lot of cities domestically" because there is almost always a Holiday Inn Express somewhere.

But really, you should figure out how you would plan to redeem points to try to figure out a value for each chain's points.

If you are interested in quantity over (high-end) quality, you might have valuations like mine:

SPG = $0.014
Marriott = $0.011
Priority Club = $0.004
Hilton = $0.003

Then you can compare both day-to-day earning and signup bonuses against the value you will receive. Here are some recent signup offers:

SPG 30k, Marriott 70k, PC 60k (80k targeted), Hilton (2 cards @ 50k+)

Note: Many of us prefer a 2% cashback card for daily spending. Think about how much you'll really get from hotel cards for redemption value vs. just taking the cash.