I personally prefer squeezing to kicking and slapping (though i'm not opposed to them either) because squeezing has two unique characteristics:
(1) more physical contact, and a sense of "connectedness" and
(2) the pain ends immediately upon release of the balls (at least that's been my experience - if anyone squeezed my balls to cause lasting pain I would consider it excessive).
As for squeezing a ball bag to achieve a rupture, I personally have no desire to see or experience that. about 10 years ago, I had the occasion to get my dick whipped by
Mistress Shane at a New York fetish club. She smacked it three times, and I have to admit the first two hits were awesome. My dick had swelled to proportions I had never seen before. The third time, however, with all the blood in my dick, she ruptured the large vein running down the shaft. I was rightfully worried that I had done permanent damage. Fortunately, the bartender gave me some ice and the huge purple welt finally calmed down. I had a blue dick for 10 days, however, and I learned that you only get one dick in life, and similarly, you only get two balls. If you play irresponsibly, you lose your toys forever.
From what I've seen, more women prefer kicking balls than squeezing or slapping them - certainly that's the case in contact with relative strangers. It's plausible that a guy could go to a night club and successfully ask a couple girls to kick him in the balls then and there, but I can't imagine a grab request being satisfied.
I think a good poll would be to ask only women what they prefer to do - kick, squeeze or slap (perhaps "electrically shock" should also be included).