Effect sizes - Friedman's test

Hello, I have a question regarding which measure of effect size to use.

For Friedman's test, do I report the effect size when the result of the test is insignificant? For example, Field (2014) only reports the effect size of the post-hoc tests, but not the effect size for Friedman's test. If I do have to report it, what effect size should I report? Would it be Kendall's W? I've seen in other studies that they sometimes report either η2 or r.

Thank you!