Aha! Well, that depends: the missionary position would seem to me to be preferable for initiating or renewing a sexual relationship, because of the entire-body-length, skin-on-skin contact it affords, and because the two lovers can easily see into each other's eyes during the act. Also, it'd likely be more easily entered-into (pun intended) for a "quickie". Contrariwise, the "doggy" style is "nature's way", allowing maximum penetration, and ideally lines up the penile orifice with the cervix, important if impregnation is desired. I guess it's a matter of the couple's preferences.
Oral sex as foreplay or afterplay?