I should probably vote for The Burning or The Fog (both of which are fantastic releases), but I'm going to give a vote to Body Bags instead. I think it's just an extremely fun little movie, plus it's a HUGE upgrade over the severely edited fullscreen DVD while both Burning and Fog already had quality DVD releases. There is a little audio hiss in the dialogue near the beginning of "The Gas Station", but this is a movie that I never imagined would make it to blu-ray, let alone in a special edition with a nice retrospective featurette.
Plus, I'll give honorable mention nods to Night Of The Demons 2, Ticks, and Just Before Dawn, three favorites of mine that I'm overjoyed to own in hi-def. Just wish the featurette from the Just Before Dawn DVD was carried over. Regardless, 2013 has been an incredible year for blu-ray collectors. My credit card statements have been ridiculous of late thanks to all the cult labels out there.