Is mono or fireline better when deadsticking?

Unless I am fishing very deep (say 40 feet or more) I use mono or flurocarbon for dead sticking. Remember that one of the things you are trying to do with a dead stick is to detect a bite (by seeing the rod bend) without the fish feeling too much pressure and dropping the bait before you can set the hook. By using mono (I typically use 14 lb Vanish Flurocarbon) you get some stretch in the system and the fish is less likely to detect you. I use 14 pound Vanish because it is invisible to the fish so the extra strength means I will rarely if ever break off on a big fish.