You need to prep the plastic surface well to get either coating to stick and NOT peel away. Sand blasting lightly is best, but sanding should work if needed.
Krylon is cheaper and far easier, once the surface prep is done, shake the can and spray, but will wear away faster than duracoat.
Duracoat, you'll need to purchase extra stuff, (air brush and compressor if you don't have one, or the spray bottles, measuring cups, etc) BUT, if you follow the instructions and measure out things carefully to mix it in the right proportions, as well, clean and prep the surface properly, you'll get a coating that lasts longer and will be a lot tougher.
At least you should, my duracoat looks great and has already shown itself to be more scratch resistant than paint, but its only a few weeks old, the true test is a year or two down the road.
Remember, no matter what you choose, surface prep, surface prep and more surface prep will determine how well it turns out and how long it lasts.