In my experience - as an average guy - it depends on the girl. Some are hung up on really big ones. I find I don't click w/ them, usually, even before the sack.
Just like some guys NEED huge boobs, others are fine w/ the itty bitty titty club. Some women only orgasm w/ penetration, some can't during penetration, some with "help".
That, to me, is what makes it fun. Taking the time to learn your partner - learning to have fun together. For that, usually any size will do.
Now, that is not what the hobby is for. The hobby is for a fantasy - or for a need. Rarely the connection - though that is certainly possible.