The first one and especially the second were pretty darn amazing.
The 3rd Fable sucked pretty badly.
The first 2 had compelling stories that really kept the player interested, while the 3rd one, though it may have had greater customization, just didn't have the same pull.
Like in the first one, there is the epic quest to find the identity of yoru family, and defeat the evil Mastermind that is Jack-of-Blades.
In the 2nd, gathering the 3 heroes of strength, skill, and will sure is nice, and then the psychotic villian, Lord Lucien, has some kind of crazy ideas.
In the 3rd Fable, the story sucked. The end.