Lotus...the others are fun, but there is nothing more intimate than having your legs supporting each other and arms entwined, feeling her entire body move against yours as she rides. The ability to have full eye contact as well as easily kiss and fondle her entire body....mmmm.
Surprisingly, with my SO, missionary is the most fulfilling for both of us. For some reason, we fit so well, it is as if our sexual anatomy was made for each other. I can make her have multiple orgasms in this position and it is the one that is sure to get me off as well. Even after I have orgasmed, she can continue to grind on my pelvis, keeping me semi-hard, and still have orgasms for herself.
One of our favorite positions is when I lie on my back on the bed and he stands between my legs. He's at a good angle to watch from that position, which he likes; and my hands are free to use a vibrator while he's penetrating me, which I like. It's a win-win for both of us.