I personally use the long fiber. New Zealand sphagnum moss has been used all over the world and is known to be about the best there is for orchids. Sphagnum moss can hold up to 10 times its weight in water, so be careful with your watering and don't over water. Orchids that like to be moist do very well in this, such as Miltonias, Paphiopedilums, Odontoglossums and Phalaenopsis. DO NOT use the green dyed florist moss.
Sphagnum moss can contain a fungus that can effect some people.
It is quite rare, but caution should be used when handling it. Perlite is a heated natural mineral, and is often used as an additive in potting soil to help retain moisture and give an airy texture to the soil. It is also used to mix with many of the potting mediums for orchids. I use it with my bark, which helps hold a little more moisture. Some growers even use it alone with great success.