I’d say well written that are not a laborious read. I will keep adding. 

Ps.  I’d don’t mind boasting I’ve read a lot of books at my age (gen x) so I don’t read these books to compare to Hemingway .  If it’s in this list, it passed a pretty high bar “sniff” test.   If a book comes along that can make Oscar Wilde cream and Capote scream,  it’ll have a review.