Mechanics vs Narrative Villains

I've watched a couple episodes of Extra Credits explaining about villains. Below are both episodes.

Part 1

Part 2

Obviously, narrative villains fit right in with RPG Maker games but Mechanic villains can also.

Being a dungeon master a few years back, I find creating narrative villains easier then mechanics villains. I usually write up a back story on how and why the villain came to be and what their motives are no matter how crazy all while trying to ground their story into the world I'm creating.

What steps do you take to create the villain that is right for your game? Which do you find easier to create: mechanic or narrative?

I can't say that I've ever really made a strictly "mechanic" villain, but then I've only ever really done straight-up RPGs (video and pen-&-paper). I try to treat my game villains the way I would my literature villains, giving them a real, believable reason for being a villain.

Villains can be tricky. The natural instinct is to focus all our attention on the heroes we create, and their allies. Heck, even things like currency and language get more thought than villains in a lot of stories. But the villain is the reason the hero exists. Otherwise, he's just some guy with over-moussed hair. The villain is the driving force of the story.

(This is, of course, referring only to "Man VS Man" plots and not "Man VS Nature" or "Man VS Himself")