"Rules of Engagement: Violence and Hyperreality in the Buffyverse" by lostboy_lj may be my "if you only read one meta from 2012" choice. Why Buffy and Spike's relationship in S6 is not directly analogous to abusive relationships in RL, using "Smashed" as it's focal point.
"Buffy, the Vampire Slayer vs Buffy the Vampire Slayer" by beer_good_foamy. Most post-modernist thinky-thoughts; how the show's title represents the central problem of the narrative for it's titular protagonist, and how Buffy resolves her dilemma in "Chosen".
"Word of Willow: "Witch", Mirrors, and Mommy Issues" by local_max. What I hope to be the first of several Willow-centric essays from someone who has plumbed the depths of Willow's character more thoroughly and compassionately than any fan I know of.
"Warren Mears" by itsnotmymind. Draws parallels between Warren, Faith and Spike, how they mirror, intertwine and intersect thematically and within the story itself, and what they represent re: Buffy's psychology. Wonderfully complex.
"Where Did I Go? A Farewell to the Buffybot" by mcjulie. One of the few essays I've seen in these parts about one of the Buffyverse's most memorable characters. (While I'm here, I'll note that mcjulie has also taken on the awesome task of continuing the "Episode Polls" and discussion where gabrielleabelle left off, starting with S5's "Tough Love". Especially recommended is her poll and meta commentary on "The Gift".)
Also posted on Dreamwidt http://buffyversetop5.dreamwidth.org/329