I wouldn't compare the Current 93 original ro RC's version. They're completely different genres of music, they're bound to sound different. I personally prefer RC's cover, but C93 is still an enjoyable band.
Seriously... at first I was really bummed when I found out that this wasn't a Rotting Christ original... But seriously, check out the original by Current 93. I know you'll have your doubts at the beginning; but if you keep listening; it's seriously the most metal vocal performace you'll probably ever hear in your life. It's fucken brilliant.