Personal Jesus is easily Mansons best song, even if it is a cover.
And yes, Cash's Hurt is epic. Very.
Alien Ant Farms Smooth Criminal is far better then the original too.
Though quite possibly the worst, by far, is My Chemical Romance and The USed - Under Pressure.
That is quite possibly the only cover so horrible that I feel they should beaten within an inch of their life for desacrating a masterpiece.
And don't get me wrong, I actually enjoy quite a few of MCR's songs, and a couple from the used. But GOD that was so horrible.