If I recall (and believe) what I've read, moss "quality" differences are due to the species used, with some being thicker, fluffier, and longer-stranded.
That said, there is nothing better than 5-star New Zealand sphag, but as Kim said, it is quite pricey.
I stock a 4-star version that is a lot cheaper, but still quite good, and I can also assure you that there are Chilean mosses out there that are every bit as good as the slightly lower-rated NZ materials.
Chilean does not seem to last as long, hold as much moisture or stay as open and 'fluffy'. Re-potting more frequently may be necessary, depending on your growing conditions. With both there are various levels of quality.
Willgro (in BC) sells Chilean (only) directly and also through many retailers. I have not used theirs yet, although it is said to be very good quality.
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DaveW
"Every time you spend money, you're casting a vote for the kind of world you want." ~Anna Lappe