I like my 6 inch readers and at the font size I read, they have about the right amount of text on the page for me.
I haven't ever seen a 5 inch reader in person. I found an old review that shows a Kobo Mini and a Kobo Glo side by side - i was surprised at how big the difference was.
https://the-gadgeteer.com/2013/09/04...eaders-review/