One of my favorite authors is Shannon Hale. She wrote The Goose Girl, Tale of a Thousand Days, Princess Academy, just these really awesome fantasy books. I read them as like a preteen and they're very appropriate for my age and just a really beautiful, unique writing style which I really liked so I totally recommend all of Shannon Hale's books.
My favorite all-time author is Laurie Halse Anderson. She does historical fiction and it's great for young adults. I enjoy reading young adult books because they don't have all the nitty-gritty gross stuff that some adult books have, but still has a lot of the really good plots. So, Laurie Halse Anderson.
Probably my favorite author of all time is Gerald N. Lund. He writes a lot of books about the Church of Jesus Christ of Latter-day Saints and kind of its history, but he writes them in a fictional light, so it's like historical fiction type genre, and I love his books. He has one about the Martin Willey handcart companies that I really love called Fire of the Covenant. He also has another one about the Hole in the Rock pioneers called Undaunted. I've also heard his Work in the Glory books are really good, although I haven't read them myself, so I definitely recommend Gerald Lund.
This is probably going to get said a thousand times, but Brandon Sanderson, if you've lived in Utah or anywhere around, I mean anywhere to be honest, he's a huge author, kind of like the new modern day Tolkien. He's written a lot of really good fantasy books. Start with the Mistborn trilogy.