Topic says it all. I actually have yet to read Deception Point, but I voted Digital Fortress anyway. I'm a huge fan of plot twists and even though Dan Brown seems to like to use them in every one of his books, Digital Fortress kinda pushed it with them. The whole code thing was great as well.
Also, despite the praise Da Vinci Code seems to be getting, I actually found it the least interesting compared to the others. It was good all right, but just didn't compare with the other two IMO.
Also, if for some reason you decide to talk about spoilers... just warn, you know.
~Zak