Clarity

 According to Merriam-Webster:

clar·i·ty
noun \ˈkler-ə-tē, ˈkla-rə-\

: the quality of being easily understood
: the quality of being expressed, remembered, understood, etc., in a very exact way

: the quality of being easily seen or heard

According to good writers and editors everywhere:

Clarity is non-negotiable. 

That means, do not forsake clarity for style, ever. Writers who do just that irritate me to no end. And yet, those same writers have taught me some valuable lessons.