iOS's keyboard is the worst thing about the entire platform IMO. The first thing I do on any new device is replace it with the Google Keyboard. Text entry is one area where Android really outshines iOS.
And "upgraded" androids are much worse : you select a textfield, takes seconds to place a cursor in it, and multiple seconds to reflow the screen and show the keyboard.
Mind you, I have sworn off Samsung, since their TouchWiz has indeed been a laggy mess in the past. But in my experience over the years with HTC, Sony, Moto, or most recently Nokia, text input is fine. (And definitely less laggy than on my - admittedly old - iPad 3.)
Again, personal experience only.