Micro G is the worst option as it requires privileged access to your phone. This is the same major privacy issue with the regular Play Store. The only real difference is your shifting trust from Google to Micro G but, you shouldn't be trusting any third party with that type of access.

Aurora is a decent option as it allows you access to the Play Store without needing to actually install the Google Play Client.

I would say sandboxed Google Play is the best option. You get full access to the play store while still having the protections of a sandboxed app.

A lot of people will offer f-droid as an alternative but it also comes with some big issues. I'll quote privacy guides here

Due to their process of building apps, apps in the official F-Droid repository often fall behind on updates. F-Droid maintainers also reuse package IDs while signing apps with their own keys, which is not ideal as it gives the F-Droid team ultimate trust. Additionally, the requirements for an app to be included in the official F-Droid repo are less strict than other app stores like Google Play, meaning that F-Droid tends to host a lot more apps which are older, unmaintained, or otherwise no longer meet modern security standards.