Sitting on my lap, and then she leaves forward so she's on top of me.
But I also like to hold her from behind, kiss her on the neck and lift her up. I read about some girl saying she liked it when her boyfriend held her up by her breasts. I tried that with my girlfriend at the time, and she loved it.
Sitting on his lap so you can grind and tease him while he can still have access to anywhere with his hands. Also a really great position to start out in control, but then have him lift you up and then flip it over so he's on top of you!