Both. Gives me control in either position. The view up from between her legs to between her tits and watching/feeling her body language, hands fondling and squeezing or holding her around her hips so she can't move. If she's on my face facing away in more of a '69, squeezing her ass, tonging and sucking her clit, reaching down and squeezing her tit, or pulling her by the hair to keep her mouth off my cock until I tell her she can have it.
While she's riding, both hands free to grab some ass or tease a finger around/into her ass, squeeze her, tits, spank, pseudo choke, pull hair, all while holding her down to the base of my cock and letting her feel it pulsing while I low-tone growl orders into her ear... "who owns this pussy now... "