According to how everything went down, it has to be Sansa. Which is awesome. I hope she's on the lam now, trying to sneak away. I remember back in s1 I thought she was going to marry him and either poison him or strangle him as he slept.

Maybe it wasn't her, but the signs do point towards her a lot more than anybody else

I know I picked a Lannister to die this season, but I must say I was surprised by this. I thought if Joff was one to die, it would be by Tyrion retaliating after he murdered Shae, but I didn't think much more about it because that path ultimately didn't make much sense anyways. His death shouldn't have been that hard to see, though, because of the Stannis leeches, which obviously worked with Robb