It's horror movie season in the US and my favorite type is zombies. I also love campy B movies. Watching Dead Snow 2 right now and I think it ranks up there with Shawn of the Dead and Evil Dead 3: Army of Darkness.
Since you asked the favorite, i will have to describe it, trying to avoid the spoilers.
It is a masterpiece on many aspects at the same time. It is a historical movie, focusing on an isolated devout settler family living on the frontiers in the beginnings of US history. It is a dramatic and heavy movie with believable people, showing their realistic hardships in everyday living, how they really live and think the world through their strict religion, and how they react realistically to the supernatural events that unfold. It is a Horror movie that gradually builds the mystery, tense and fear thorough the relatively long stretch of time it takes (months i guess), and the actual terror moments felt deserved (i.e. not a cheap scary gag).
For all that, it is considered one of the more 'artful' horror films out there, and i'm sure it will (or already is?) considered one of the Greats in the genre with Dracula 1932 and The Exorcist 1973. It however leans on being slow and heavy, not good if you seek a lighthearted film.
The language is brilliant. At first you have to pay very close attention to understand them, but as the movie progresses you quickly get in the groove. And Anya Taylor-Joy, my god.
One way I like to describe it is that They took one this witch trials account/documents, took it at face value and just recreated it as an historical movie.