Books are great! My favorite genre is fantasy, particularly high fantasy - think Lord of the Rings style.
In no particular order, here are some books.
While not everyone finds it easy to get into Lord of the Rings, it definitely deserves a place (or at least a mention) on any fantasy reading list, if only because J. R. R. Tolkein is the father of modern fantasy. Lord of the Rings focuses very heavily on world building, and the languages are particularly well-developed, since Tolkein himself was a linguist. If you find the trilogy is not quite your style, you might still enjoy reading The Hobbit.
This fourteen book series was written by Robert Jordan until his death and then continued and completed by Brandon Sanderson (Jordan prepared extensive notes, as he had been diagnosed with a terminal illness). The books are all extremely thick, so this series is a major time commitment. It is also one of my all time favorites with a beautifully developed world, extensive character development, and an epic storyline. It contains mature themes but is remarkably clean.
This six book series was written by Jim Butcher, who is also the author of the popular urban fantasy series The Dresden Files. I prefer the Codex Alera, mostly because it is high fantasy. Both series are a much lighter read than Lord of the Rings or Wheel of Time. Fun fact: Apparently the inspiration for Codex Alera came from a heated debate about whether a strong enough premise could carry a book despite a lousy writer, or whether a lousy premise could be made up for by a strong enough writer. The conclusion of this was Butcher agreeing to write a story using two terrible ideas provided to him, which ended up being Lost Roman Legion and Pokemon (Johnson, 2010).
Johnson, B. (2010). Jim Butcher chats about Pokemon, responsibility, and changes. Fantasy Literature. http://www.fantasyliterature.com/author-interviews/jim-butcher/
This seven book series was written by J. K. Rowling. To be honest, I have a love-hate relationship with this one. It's an incredible and imaginative world, but, given that it began as more of a kids' adventure, there are a lot of plot holes. Also, J. K. Rowling keeps trying to say things about the world, but for my sanity I consider everything from the 1st book to the right before the epilogue is the last book as canon, along with Tales of Beedle and the Bard, Fantastic Beasts and Where to Find Them (the book, not the movie), and Quidditch Through the Ages. The epilogue falls somewhere between canon and not. Everything from Pottermore or The Cursed Child or elsewhere I consider unequivocally not canon. If you are a person who tends to care about these things, for your own sanity, I recommend doing the same.
This trilogy was written by Elizabeth Moon. There is also a sequel trilogy. Moon writes a lot of science fiction, but this represents an extremely successful foray into fantasy writing. The Deed of Paksenarrion is military focused (Paks is a warrior by trade) and is very strong in detail. The story is harsh at places, but I would strongly recommend it!