Red Hugh, by Robert T. Reilly. It's a really quick read (like you could read it in a couple hours), and I don't know why, but I've always enjoyed it. It's not a complex book, but it's...I don't know. I just enjoyed it a lot. Classic knights and castles, princesses, prisoners of war, etc.
Also I like The Hobbit and Lord of the Rings, but who doesn't?