Help! If you work with Ruby on Rails, I need your hot takes!

It'd really help me prep for our RailsConf talk if you could look over rubocop-rails' cops (or better yet, look at your own config) and reply with the rules you feel strongly about (pro or against).

We want to make the most of our session, and to do that we need to order these rules by "spice_level desc"

https://docs.rubocop.org/rubocop-rails/cops.html