Daughter of the Empire / Servant of the Empire / Mistress of the Empire trilogy by Raymond. E Feisthttp://uk.ask.com/wiki/Daughter_of_the_Empire?lang=en
Very well written and I found it gripping. Lots of fantasy based magic stuff but the plot and the clever way the lead character solves her challenges is what makes the story so good.
There is another series written by the same author that fits well along side this - the Riftwar series, centering on the fortunes of a Magician-in-training. This was written first I believe and is also very good, but for me not quite so good as the Empire series. Both work as stand alone series.
Battlefield Earth by L. Ron Hubbard is also a very good read. It's not all about war as the title suggests but there is indeed a lot going on there and it just gets better the more you get into it. http://uk.ask.com/wiki/Battlefield_Earth_(novel)?lang=en Again it's very well written, with clever plot lines and out-thinking going on....
Don't watch the film - it's absolute pants.
Currently I'm on the Wheel of Time series by Robert Jordan. So far so good, and I hear it gets very complicated, but I'm not very far through it yet . It was meant to be a decology and each book is quite large in it's own right, but it grew to a series of 15, so it's taken me a long time to pluck up the oomph to get stuck into it as I know it will take me ages to go through it! It's very enjoyable so far though
For non fiction
I like Theodore Gray's books, especially Elements Vault, http://www.periodictable.com/index.html
but there's also a really good little book called 'What If' which gives serious but humerous answers to daft and generally impossible questions/scenarios.
I'm not sure about favourite book of all time, but a series my mum recommended to me recently by CJ Samson is really good. It's about a lawyer in Tudor England under Henry VIII who solves crimes and helps with cases ... it has some really dark bits in but it's really good if you have any interest in history or like thrillers/mysteries. I've read the first 5 and have one to go!
I am also a big fan of the Redwall series by Brian Jacques. Couldn't put down "Pearls of Lutra". Also love the Discworld novels by Terry Pratchett.
"World Without End" and "Pillars Of the Earth" by Ken Follet, both brilliant and probably the best books I have ever read.
I've got lots of favourite books, but one is "Jane Eyre" which I return to every few years. Another is "Cold Comfort Farm" by Stella Gibbons, especially as it's set in Sussex! Also "Diary of a Provincial Lady" by E.M. Delafield. Both those last two make me chuckle!
1. All time favourite books -- they're a series so I count them as one -- The Hyperion Cantos by Dan Simmons. The books, by name, are Hyperion, The Fall of Hyperion, Endymion, and The Rise of Endymion. I could write a book on how brilliant this series is. If you like science-fiction, read these. They changed my life. They truly did.
2. Sliding in at an easy second place is Notre-Dame de Paris by Victor Hugo. The character Pierre Gringoire is as if Hugo had looked into the future and written me into his novel. I love how this book is funny and serious and full of history, and of course, I love to read about myself.
3. Back to sci-fi, The Left Hand of Darkness by Ursula K. Le Guin takes the prize for number 3, and is also where I got my user name from. In this book, Gethenians are a race of people from the planet Winter who have no gender. The story follows a human male from Earth, Genly Ai, as he tries to convince the planet's political leaders to agree to join the Ekumen, which is... basically just the Federation of Planets from Star Trek. This book is a fascinating study of gender politics and a cold-weather survival thriller. I adore it.
Back to the classics, I have to mention The Wind in the Willows by Kenneth Grahame, because it IS one of my favourite books of all time -- it really doesn't belong beside a number on this list. It's too timeless and too perfect to be ranked.
I could talk about books all day, but I'll limit myself to just four for now instead of giving a top ten list. The top ten includes basically a lot more Dan Simmons and a bit of China Meiville, with some Tolkien sprinkled in because who doesn't love Tolkien?