It depends. Would you rather be in extreme humidity, where all the moisture in your body is practically sucked out through your pores? Or would you rather be in extreme dryness, where you're constantly, unbearably thirsty?
In the same vein, would you rather be freezing cold, or burning hot? Would you rather be in a place with tons of wind, or lots of storms?
This question is really asking for your opinion here, but if you ask me, since I think that dehydration is the worst way to die, I think that arid conditions would be the most difficult for me to face.
Hope this helped. :)
