General Fap-
My overall experience has been girls resist more when they're on top.
My suspicion is the person on top feels like she is in charge. So she feels more confident to deflect, deny, resist, etc.
When she's underneath, there's more of that girly "surrender" feeling. So she's more likely to comply and go with it.
Another downside to "girl on top" is it's usually quite hard to reach her vagina. Which is really the primary spot you should be escalating towards. It's easier to play with breasts when she's on top, but I usually try to ignore breasts altogether until my cock is in her (at which point, if she isn't topless already, I will get her topless, because I want her breasts out).
That said, I've had a few fun experiences escalating with girls on top. It's not horrible or anything.
If you're interested in it, I'd suggest you try this position out. Maybe you'll find girl on top works better for you. Different things work differently for different men.
Chase