I DO mostly use coconut husk chips for most orchids, bark for a few (including Phals), but I have grown a couple Phals in sphag for a bit, and have now a few orchids in small pots potted in sphag. Sphag DOES need replacing annually, so I don't use it for too many of my orchids.
I really like the NZ sphagnum moss. I use it to top pots of orchids that need a little more moisture than my red lava rock alone can provide. I was never fond of the moss from the box stores.
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I have never had much success using bark or bark mixes so that is the one medium that I avoid using. I much prefer the NZ sphagnum moss if the orchid does not like the lava rock...or mounting the orchid.