Copyleft, and AGPL specifically, seems like a good fit for large applications, whereas more permissive licenses work well for smaller libraries.
With libraries it's obvious that you are doing it for the benefit of application developers and most of those are proprietary but they are not competing against you, they are collaborating. Therefore a permissive license for libraries is a much better choice.
"It is not worth the trouble to use copyleft for most small programs. We use 300 lines as our benchmark: when a software package's source code is shorter than that, the benefits provided by copyleft are usually too small to justify the inconvenience of making sure a copy of the license always accompanies the software."
[0] https://www.gnu.org/licenses/license-recommendations.html#sm...