best

Indeed many solutions directly filter out string values and leave everything else in the list, but as @Chrono79 said the Kata input only consists in intgeres and strings.
Furthermore, there exist realistic cases in which one can be interested in retaining only integers or filtering out only specific data types.

... takes a list of non-negative integers and strings

The input contains only non-negative integers and strings.

this doesn't filter out the strings but allows only ints. If the source data had booleans or other data types this algo would lose all those other types and only preserve ints, which is not accurate to the request.

Clever, but I don't think this is really best practices.

thanks for your explaination. I got stuck at that