@lucy People use GPLv3-or-later over AGPLv3-or-later as the GPLv3 is a free license, it is well known and is also named as a compatible license in some other licenses (although those licenses really don't matter).

Businesses like google cope and seethe if you license AGPLv3-or-later, as that puts a stop to their degenerate behavior where they take free software, add spyware and other malicious functionalities to it and run it on their servers - they would of course still have permission to do so under the AGPLv3-or-later, but they would just need to make the modified source code available to the suckers. But it turns out that google doesn't want to publish hard evidence of their criminal activities.

I personally license AGPLv3-or-later.

Whether you license AGPLv3-or-later or GPLv3-or-later for software that isn't really useful for SaaSS doesn't really matter in the end, as those licenses are compatible.