The last set I bought was fleece from Gander Mt. on a great clearance, but the very first time I dried them, they melted in quite a few spots, we still use them but I was so bummed, we love the feel and warmth of the fleece, even my DH who is usually warm, loves them.
The set before that I bought organic cotton set from BB&B, they didn't even last a year before they had 2 large holes in the fitted sheet, it was really strange. But the top sheet was really large, like they had mistakenly put a King size top in the Queen size package, so I cut off one side and patched it with the extra part of the top sheet, hopefully we can get another year out of them, because they are comfortable and have a nice silkie feel to them.