Whichever sounds more natural to you, because the whole countable/non-countable less/fewer is crap made up by Edwardian snobs and then repeated by school teacher gammarians too into being “proper”. To quote wiki

The comparative less is used with both countable and uncountable nouns in some informal discourse environments and in most dialects of English.[citation needed] In other informal discourse however, the use of fewer could be considered natural. Many supermarket checkout line signs, for instance, will read “10 items or less”; others, however, will use fewer in an attempt to conform to prescriptive grammar. Descriptive grammarians consider this to be a case of hypercorrection as explained in Pocket Fowler’s Modern English Usage.[7][8] A British supermarket chain replaced its “10 items or less” notices at checkouts with “up to 10 items” to avoid the issue.[9][10] It has also been noted that it is less common to favour “At fewest ten items” over “At least ten items” – a potential inconsistency in the “rule”,[11] and a study of online usage seems to suggest that the distinction may, in fact, be semantic rather than grammatical.[8] Likewise, it would be very unusual to hear the unidiomatic “I have seen that film at fewest ten times.”[12][failed verification]

The Cambridge Guide to English Usage notes that the “pressure to substitute fewer for less seems to have developed out of all proportion to the ambiguity it may provide in noun phrases like less promising results”. It describes conformance with this pressure as a shibboleth and the choice “between the more formal fewer and the more spontaneous less” as a stylistic choice.[13]