I love this answer from Buffer’s Kevan Lee (via email):
“I brake for visuals—images, videos, animated GIFs, Vines, you name it, I’ll look at it.
“Visuals spur nearly double the engagement than text does. If you usually get five likes per post, get ready for 10. If you normally draw 10 clicks, here come 20!
“And the best part: adding a visual is quick and easy.