High humidity is more important.
I beg to differ. I've heard that the most important thing is air circulation, but temp and humidity, I'm not quite sure, I think temp might be more important.
Why is because I've heard that if they have no air circulation, they die. I've read around the forum that people's Nepenthes still pitcher with humidity less than 50%. Examples such as ventricosa and sanguinea (I think sanguinea) are highlanders, but they can pitcher with low humidity. Temperature is important because if they don't get a what is recommended, they can die (talking about other Nepenthes). If they get into Winter weather, good-bye. This is my opinion, though, someone with better experience will hopefully post.