Well, everyone knows what my poly of the year is since it's simply my favorite, so let's see...poly of 2012? This wasn't a huge year for strings aside from 4G. Nonetheless, since I discovered it only this year (personally I mean), I going to say Discho Iontec. Does absolutely everything well. Could be better in tension stability, but it's just phenomenal everywhere else.
I also give a nod to BHB7, but it just wasn't for me although I know of many who like it.