Thanks for so many interesting responses. They show such a very varied interaction with eReading and will be great for my dissertation.
As soon as I have collated all the responses I will make the information available on here, if anyone is interested, to thank you all for being so helpful
The question about devices seems to be quite controversial and has shown me how many there are available globally. I think it would have made a very very long question if I had included them all, but did not mean to neglect Android, I use a Kobo Vox myself and think of the brand rather than the OS.