Instinctively attracted to the Kindle scribe because I love writing on books as I read them, however I've been disappointed by every device that's taken a crack at this, and I've tried them all. Nothing beats paper, which sucks because digital formats are infinitely copy able, backup able, etc.
I always wonder how they implement write-in-books. Never found a FOSS version. I wanted to add it to an android e reader maybe so at least I could try write in books on various Android tablets or a zfold. Failed at that too!