What is your preferred coding style? Such as those imposed by Checkstyle.

It doesn’t have a name. Basically whatever Xcode has as the default, plus some minor adjustments.
No single letter names, consistent formatting, comments only when really needed.
Those are some good examples.

I hate overly opinionated styles, especially when they enforce completely retarded rules.

Some check style rules are meaningless and was invented just for the invention purposes. Checkstyle, PMD, spotbugs are decent enough

In the end, any style checker/enforcer should encourage and guide the devs towards

1. Easy code readability
2. Future maintainability
3. Avoiding code smells
4. Refactoring Complex code which don't adhere to SOLID principles
5. Common mistakes or bugs occuring in that programming language or framework or lib