Every way has its merits.  
With you on top, looking in your eyes' with my hands free to hold you and do other things is fantastic.
Doggie has the deepest penetration, and the view of tan lines is wonderful.  
Mish with legs wrapped around me is awesome.

Bottom line is there are no wrong answers!

B, so my hands are free to roam.  (makes it easier on my back, too)

LLAP,
Swim

Either one works for me.

Totally depends on the lady.  Petite = B.  Tall/curvy = A or C.  Variety is the spice of life however.

You missed the option where she's behind with the strapon.

missionary.  I love good DFK, and in mish, you are therefore connected in two places, completing an electrical circuit of sorts.

B+C= RCG
= Great visual
+ Max penetration
+ She positions herself for max result