I bought the official leather sleep cover. I think I bought it from the same seller as you.
I like the way the cover looks, like a little hard cover book. The cover is sturdy and the reader clips pretty tightly into it.
What I don't like is that you can't fold the cover all the way back. It makes the reader bulkier and less comfortable to hold. I'll keep using it though.
But, if I were buying a case now, I'd check out the
kwmobile cases on Amazon. The front flap folds all the way back and the case is thinner.