I just switched from JSHint to ESLint to try it out. So far I haven't noticed too much difference (I use it with SublimeLinter)

Wasn't aware of the custom rule thing... Does anyone have any examples of good custom rulesets?

The Airbnb styleguide and matching ESLint preset is quite popular and very complete: https://github.com/airbnb/javascript/tree/master/packages/es...

To add to this, Mozilla have their own ESLint preset: https://dxr.mozilla.org/mozilla-central/source/devtools/.esl...