To be fair, I think Slap Happy was the series that really got the ball rolling on gag/choke/puke/throatfucking.
And of course, Granddaddy Max Hardcore was the first to regularly put the girls in the now-familiar upside-down-head-hanging-off-the-edge-of-the-couch position for optimal deep throatfucking. Don't get me wrong, I love the Factor series, I wish they came out more frequently. But Max and Brandon were pioneers.