I have couple of my phals mounted (upside-down of course...lol) and most of the others are in fir bark, charchol and perlite. Two are in spag/cork chunks but the three that are in the for bark mix are the only ones that are in spike.
All mine are in aliflor and clear pots. Seems to be the answer to my some frail looking phal from the past. I do have one that is in a white plastic pot and it surprises me as it is one of my healthiest ones. I am not really convienced that phals care there type of medium to cover there nosy root tips, they just like to have there feet damp but not wet and allowing them to dry a bit works well for my growing conditions.
Mine were in sphag then I repotted in store bought Phal mix. Sphag holds too much water for my growing habits and they seem to be doing better in the new mix.
My phals are mostly in a mix of sphag and perlite and they seem to be happy. The perlite helps get air to the roots and they don't stay wet as long as with all sphag.