On your back vs On your knees....

Just a question I was pondering, when I am taking a nice hard cock in the ass do I like being better on my hands and knees or on my back legs in the air. Both have there positives. I love the feel of hands on my hips pulling me closer so I take every inch of cock. Maybe even that occasional hand on my back pushing me down so my face is on the pillow just getting pumped. Such a wonderful feeling. Being on your back has its perks to. I am flexible enough that I love being able to put my ankles on a pair of shoulders, having a set of hands wrapped around my thighs while being driven hard and deep. I get to see the look on there face when they drop their warm wet load inside my ass. So which do you prefer when you are giving or receiving?