Nobody is saying that these are top professors, only that they suggested some books to the curators of this project.
The two main dimensions would be Research and Teaching. A third might be Public Engagement. But there's not much correlation between these.
When I was doing my PhD in Physics I've seen professors doing brilliant research but horrible at teaching or explaining concepts in an understandable way.
Richard Feynmann was a rare exception excelling in all three dimensions above.