G was such an easy choice, this man... John Green. The first of his books that I read was Paper Towns which had been recommended to me by a colleague of mine. We both used to work at Waterstones so were pretty hot on recommendations but John Green had passed me by (I hadn't discovered the rich seam of Young Adult fiction at that point). I was immediately hooked on all of John Green's books, he is such a great author and someone who I would consider to be an awesome influence for young adults. His YouTube channel is amazing, in particular his exploration of the cost of healthcare in America.
John Green is a decent human being, and for that reason alone you should read ALL of his books.
Here is a recap of my A-Z so far: