You can use "much"
or "most"
based on the quantification that seems appropriate to you. "Most"
is the superlative of "much
", so depending on how much of the stain remained, you can use the appropriate word.
Someone like me would use "most"
even if 50% of the stain remained, and "much"
if 10% of it remained, whilst others might have a totally different threshold of differentiation.
Adding some explanation regarding countable/uncountable:
If the query was about a "number"
of stains
, as in:
"Despite John's furious scrubbing, many/most
of the stains
remained."
Emphasis being on the plurality
of stains, then you will have to use many/most
, depending on your threshold of differentiation between many
and most
.
But, the opening post is referring to the intensity
of the stain, that is the quantifiable as an uncountable, therefore, in this context you must use much/most
, depending on your threshold of differentiation between much
and most
:
"Despite John's furious scrubbing, much/most
of the stain
remained."
I hope this clarifies the questions that some had, regarding it being an uncountable vs countable.