I like both (and frankly a few other positions as well).
I've had 2 black lovers. The first was a skinny guy with a pretty long, skinny cock. Missionary with him was great since he was a great kisser and kissed me long and deeply while buried inside me. He also loved to suck on my nipples while we fucked. I'd almost always wrap my legs around him since it was so easy. He really understood how much I liked that close contact. The best with him, however, was doggy style. The second time he had me, I was on my knees bent over a footstool in his living room. That long dick of his was fabulous!! He held onto my breasts while that long dick reached all sorts of places
The second guy was a one night stand and it was missionary the first time and then he had me sit on him the second time. That man was obsessed with my breasts, so he played while I came twice on his cock. It was a very good night for all.
I think my fantasy would be to find a guy with a pretty long, but certainly thick cock. He would hold my legs spread wide and very slowly push his thick hard cock into me so I could feel it stretching me little by little. It would be up to him to set the pace since I couldn't stop his thrusts, but he would know to drive me crazy by slowly stretching me until I had taken it all.