You could do worse than look at user "geocar"'s comment history on HN; he mostly talks about the array language K rather than APL, but he argues a lot about code size, conciceness, readability, expressivity, etc. more than individual operators or functions. e.g. these and the comment trees around them:

https://news.ycombinator.com/item?id=10876975

https://news.ycombinator.com/item?id=8476113

https://news.ycombinator.com/item?id=27223086

https://news.ycombinator.com/item?id=25484587

https://news.ycombinator.com/item?id=25903740

https://hn.algolia.com/?dateRange=all&page=0&prefix=false&qu...