I think it really depends on the categories, your typical redemptions, and net expenses. What categories are your weak spots?

I have a setup with Amex Plat for flights (personal or company), AA Citi Exec for hotels on company dime, Chase preferred for personal hotels, rentals and dining (also has a 10% anniversary bonus), freedom flex for gas (Gas quarter) and general-use gift cards (Paypal quarter), Walmart Capital One card for Walmart groceries (pairs well with Amex Walmart+) and Chase Freedom Unlimited for the rest. I will eventually get the C1 Venture X (2%) to replace what freedom unlimited does now (1.5%) and allow me to transfer the Walmart card points to miles.

Valuing Amex MRs, Chase URs, C1 miles and AA miles at 1.5c, I'm getting at least a 7.5% on flights, 30%+ on hotels, 4.95% on dining, 7.5% on gas, 7.5% on groceries. The Vanilla gift cards also help with these miscellaneous expenses upto $1.5k per flex card that you have, buying them with Paypal at CVS effectively gives you 10.37% cashback on anything factoring in the $5.95 purchase fee per $500 gift card. Outside these, there's a floor of the C1 2 miles = 3% on pretty much everything else, except rent, where a Bilt Rewards can get you 1 mile or 1.5% back. There's also Citi Custom Cash for 5% on niche stuff to earn ThankYou points upto a limit. The annual fees of the above pay for themselves independent of the cashback with the other perks (at least the ones that actually matter to me, not the Peloton or Saks credit).

In every category except for dining, I don't think there's a cashback card that does better. Some folks value Amex, Chase and C1 points at 2c. Then there's the whole idea of churning which beats all of the above.