I can't really talk about which one was worse, seeing as I haven't seen TCOR. I really liked Pitch Black, and when the prequel got such bad reviews, I just avoided it completely to save myself some disappointment. We did get Escape From Butcher Bay because of it, though. Which might potentially make up for the movie being shit.
Battlefield Earth on the other hand, I did see. It was bad. Really, really bad. But I kind of love it for that. As someone already said, the movie's so bad that it goes full circle and is fucking hilarious. I'm really into craptastic movies, and that one's one of my favourites. Believe me, get some mates together and give that bad boy a watch. It's entertaining as hell.