I all the while using both hand, never using one hand and never appreciate using one hand. I rather prefer everything to be seen in clear than tiny.
When on emergency or not applicable to use both hand, they is never an issue for me using one hand to operate it, most of the time I only use one hand during calling. My biggest phone ever buy is 6.44" Sony Xperia Z Ultra also no issue using one hand when making call.
Others usage from internet, photo taking, chatting, gaming, both hand is much preferable than one hand.
I have several phones... on my desk right now, I have the following:
iPhone SE (4-inch)
iPhone 7 (4.7-inch)
Samsung Galaxy Note5(5.7-inch)
Samsung Galaxy S7 edge (5.5-inch)
LG G4 (5.5-inch)
Google Pixel XL (5.5)
plus several random 5-inch Android phones
Like I said, ever since I got my hand on the iPhone SE,
all the other phones have pretty much been neglected....
but I do take the Galaxy Note5 when I fly or go on long
trips. If I go somewhere that require cameras, I always
take the Google Pixel XL, which has the best photos
of all those phones I have. If I go to the gym, I usually
take the iPhone 7 or Galaxy S7 edge, because only
those two are water resistant.(from sweat or the pool)