Torn at the store. It doesn't seem to matter that much about the brand, I think that all of them at one time or other are put on rolls unevenly.
I've bought sheets at a thrift store, in very good condition, and torn them mainly to get rid of the seams. On some of these, name brands, one edge left on the seams can be up to TWO inches more than the other end of the same seam. I'm talking bottom small seam, and top big seam. The side seams are more accurate in the way they tear, mostly even from top to bottom.