I'm not a fan of eye candy and turned them off in 2002, on Windows XP.That's why I would like to see them get rid of the scaling. Supply a screen that can use the native rendering. I almost got the 6s because of that. But the plus screen at 400 dpi is so much nicer I stuck with the plus when going from 6 plus to 6s plus.
I was never a huge fan of motion or transparency. I turned those things off two years ago and never missed them. Helped speed things up. Not a huge amount, but noticible.
I am anxious for apples OLED display. Not having to power the black should boost battery life. And OLED image is impressive over LCD. It's very difficult to separate out pixel density from other screen attributes when you comparing the two technologies. Thinking sweet spot for speed, efficiency, power consumption, processor load would be a 2k OLED display set for true tones.