Hi!
I respect your opinion, but the choice to move the Control Center to the top right was a necessity, as the gesture to open the Control Center and the one to exit the apps would be easily confused.
I understand what you’re saying: a larger iPhone is hard to use in one hand, and with the Control Center at the top it’s even more complicated. Even to me sometimes it bothers, since I just switched from iPhone 6s to a model without Home Button. But Apple has also thought about this: on whichever screen, go down with your finger (the opposite gesture to exit the app) and the screen goes down. The same thing happened when you put (without pushing) your finger quickly twice on the Home Button in older models. This can be convenient for using the iPhone with one hand.
On the other hand I think that if you find yourself wrong with new iPhones the best choice is definitely an iPhone SE. After all, this is one of the reasons why Apple created it.
I hope I helped you!