The fastest would be the glucose tablets or liquid they sell for type 1 diabetics. Honey that is crystallized is very fast too, as the crystals are pure glucose. Some candies like US Smarties are sweetened with glucose. Fruit juice and sucrose are pretty quick, still, but if I'm in a hurry, I eat potato or white rice.

Fat slows down absorption of carbohydrates, so chocolate, and to a lesser extent potato chips, are slower than pure potato or other candies with sugar.