I would prefer the gentle downhill for sure. I tend to think about it in terms of potential energy. Everytime I ascend I store some energy in the form of potential energy. If I descend gently, I can make use of that energy little by little. Every step feels lighter on the way down. If I have to take a steep descend I have to waist the stored energy. If I would use it, I would become too fast and hurt myself. I have to make sure I safely disperse the energy.
I do not have any preference for a steep vs a gentle climb, though. I have to put in the energy either way