Have you read The Hobbit? Do it now if you haven't, it's one of the best epics ever written. Then read the Lord of the Rings trilogy right after.
Also Ender's Game, and books following it such as Ender's Shadow or Speaker of the Dead (doesn't matter which you read first they branch off from Ender's Game) are also amazing books.
Those are my favorite Fantasy and Sci-fi book series right there, and I know a lot of people are the same with that. Those two series will make the Harry Potter series look mediocre and the Twilight series look like a pile off crap, no offense to those books they are welly written (maybe not Twilight, it is more on the mediocre line), but still.
Seriously read some Tolkien books, Tolkien is one of the best writers from the last 100 years.