The 5.4" - if the rumor and mock up are true - is *finally* going to get all the SE, 6, 7, and 8 upgrades from people complaining that the 11 Pro is *just* a bit too big.
If the mockup is true, it's still too big. Fortunately, I think the mockup is incorrect and a 5.4" iPhone 12 would be closer in size to the SE. Still bigger, but not as big as a 6/7/8.