Low contrast smartphone displays work best for me - with matte screen protectors.
Glossy, reflective, sharp, vivid & high contrast type smartphone displays are an eye strain magnet for me. Although the same can't be said for TV's.
I think the proximity & distance from the display/device, and the size, also plays a part. Smartphones/tablets are generally more compact/condensed, & held closer to the eyes than a laptop, monitor or TV.