My Favorite Book of all-time, no competition, is Ken Follett's Pillars of the Earth.
I first read a Ken Follett a few years back when I found Hornet Flight on the trader table at work. It was great, so of course I had to then read every Follett book that I could find.
Most were pretty darn good (Eye of the Needle, A Dangerous Fortune, and Jackdaws).
Others were not so great (Whiteout or The Modigliani Scandal).
Pillars was probably the 10th Follett book that I read but I had saved the best for last. I loved this book. The characters are so real. I hated the bad guy with every ounce of my body. Some of the scenes are so moving, I really had tears at time.
My daughter was reading Pillars the other night at a ballgame when the lady next to us asked about it. I attempted to explain "Well, it's about this family that's struggling thru 12th century England and the father is obsessed with building a church." I could see it in her eyes - "Wow. How interesting ...".
When World Without End was released last fall, I quickly grabbed a copy and read it within a few days. It's definitely a good read. It's set in the same general area as Pillars but about 400 years later. The characters are good, the bad bad guy is bad. For me, it just didn't have the same feeling. I'd include World as a favorite book but probably not in the top 25.