This brought to mind an article in Literary Hub which had put together a list of debut novels that are often considered to be their author’s masterpieces: http://lithub.com/10-debut-novels-that-are-also-their-authors-masterpieces/.
Also on the topic of first novels, The Center for Fiction has a First Novel Prize which is awarded to the best debut novel published between January 1 and December 31 of the award year. The author of the winning book is awarded $10,000 and each shortlisted author receives $1,000. The 2017 longlist (http://www.centerforfiction.org/awards/the-first-novel-prize/2017-first-novel-prize-long-list/) featured Lincoln in the Bardo, but the novel did not make it to the shortlist (http://www.centerforfiction.org/awards/the-first-novel-prize/2017-first-novel-prize/). The winner will be announced on December 5.