Kobo Sage vs Onyx Boox Note 3

I hope that this clarifies the whole battery issue and my attitude and my conclusion around the Kobo Sage because it's something that I kind of linger...

I now carry only this, not a couple of paperbacks, a notebook and a pen. The battery life is phenomenal! I read 3-4 hours a day 5 days a week with frequent interruptions (work, what can you do?) so it often powers off and the battery is still 50%-60% at the end of the week! The ability to change the screen lighting makes it easy on the eyes, the bluetooth connection works well with ear buds but I've only been able to bluetooth tether it to my phone once. The Wi-Fi tether works like a champ every time. My only "complaints" are: 1) setting up the google play store (for the nook and Kindle apps) is frustrating if you don't, as I did not, read the instructions (the reboot is, in fact, necessary!) 2) Every time I would tether the device the location would automatically turn on (this has been alleviated with the latest update but contrary to the update notes, location is NOT turned off by default

The text of the book is fine, the problem that he has, the menu does not increase in font size and is fine lined so he can't read it. Once in a book he can read the text but can't see the small menu font to navigate from one book to another. Even when he is at "My Books", they are so small he can't tell which book is which. Once in a while he will accidently touch the center of the screen and pull up the main menu, he can't read it to see how to get out of it

3' size, my suggestion will be to go for Boox Note 3. Even though Note air is also a great option in that size, I won't recommend it for your use case because you said you will use it on the go a lot.