I've been thinking what an artful or artificial character might be in contrast to a natural one.
You mention Mary, and I'm sure we all agree with you. What about Mr Collins? His habit of thinking up compliments and delivering them "with as unstudied an air as possible" makes him rank relatively high on the 'art' end of the scale.
I also think that Miss Bingley would be a definite contender for artificiality. And she knows it too. She knows that Darcy's "there is meanness in all the arts which ladies sometimes condescend to employ for captivation" is meant for her. I think whenever she's trying to please Darcy, she becomes fake. We see her in her true colours when she's off-guard: yawning over her book, abusing Lizzy behind her back, laughing heartily at Jane's vulgar relations. And what we see is not very attractive.
But what do you think of Wickham? Is he the epitomy of art because he lives in a self-constructed web of lies? Or would you place him on the nature side because he likes to live well: dancing, cards, girls...