Apple watch with iphone 5/5S vs 6/6+

[Network33]

I'm sticking with my iPhone 5S because the Apple watch with allow me to use Apple Pay, does anyone see any advantage of having an iPhone 6 or 6+ paired with the Apple Watch over a 5/5S/5C?

 

[AJsAWiz]

?

What, if anything, leads you to believe that there might be a difference here?