I remember pitching one of my novels to agents at a writing conference. They'd read a few chapters ahead of time, a nice perk at that particular conference, and one of the best compliments I got as I listened to the feedback was: "This is very fresh."
I asked more about what that meant. From the response, I gathered that agents look for writers who present a fresh view of life. Akin to the wonder we might have, traveling to a new place, readers also want to view life differently because of your memoir, novel, or nonfiction book.