Pencil, pen is yet another important aspect. Of course, I would like to be able to do some handwriting in pdf-articles on the margins and elsewhere, not just highlighting. I had a conversation today with a retailer, telling me that they have a pen for Ipad (ca 60€, fineline, can't remember name) that you can do handwriting with similar to paper. But didn't seem too sure.
I want to make clear that I expect handwriting short sentences & phrases in a pdf-article to be possible in a new device.
I did not expect pen to become a problem, because in the video below handwriting seemed fair enough to me. Until now I have not planned to do lots and lots of handwriting on blank pages, i.e. using the device as a notebook. But hey, if I can have it, I would like to as well.
Video specs
App: GoodNotes
Stylus: Bamboo CS 160 [it's not even fineline, guess this can make a difference]
Device: (only) IPad Air [hope the IPad to be better in this respect]
https://www.youtube.com/watch?v=g6yIdmUYRdE&t=1m59s