I carry both dyna-plugs and darts, they are each small enough that there is no problem fitting both in my saddle bag. There isn't one best from my experience, sometimes one does better and sometimes its the other. By default I have used the dyne-plug, but on holes on the side of the tire the plug doesn't get compressed by riding and the dart can do better there. Thus far I have managed to plug all holes well enough to keep going with one of the two.