Printed maps;
Nicer to use/much bigger screen/cheaper/need no batteries or a powerbank/don't ruin your brain (as much).
I do use GPS nav in the hills, but very rarely.
TBH, I think the best thing for the mind is naving without either until needed.
Navigation by common sense; mentally ticking off features as you go makes you much more aware of your surroundings and 'in tune'. Subtleties like the colour of grass, the angle of shadows, the feel of the slope, the sound of the water in the beck, footprints, etc are not marked on either maps or GPS....they can get you a long way without so much as a glance at them.
I remember an interview with a Sami herder who had never used a map or GPS. Someone gave him a map and GPS and he started getting lost; he threw the maps away after a while and went back to the old ways, which was navigation by common sense/memory/descriptive names of hills. The GPS was kept though, as he could bury food and find it quicker.