The limitation of "appeared in an ad" is a little big. There is those author highlights. Recommend one of those books, and you can't because it is in an ad? Hugh Howey for instance. I liked his Wool omnibus. I know I seen the book before KU, just could never convince myself to risk it. Have not gotten to the next part in the trilogy yet - a evil library book caught my attention and went right to the top of my reading list.
UPDATE:
Here is my recommendation for a trilogy by Hugh Howey:
- Wool (Omnibus)
- Shift (Omnibus)
- Dust