Zen

Oh easy - "It's FREE! YES, THAT'S RIGHT, FREE! 10 days of peace and quiet, food and a bed, and you get to learn an amazing, albeit difficult, meditation technique!"

At least for the Goenka retreats - which means someone is already generally inclined toward meditation.

Straight up Vipassana I generally try to sell as 'mindfulness', as it is basically what all the trendy secular 'mindfulness' practices people are pushing is, and a lot of people not yet inclined toward meditation are often turned off by any hint of 'spirituality' or anything remotely religious/Buddhist. I've tried to start more than a couple people on a pure 'mindfulness' version developed by a doctor who worked at the treatment centre I went to when I stopped drinking. He describes it roughly as -

'I studied x of the most popular meditation techniques in the world, and boiled them down to their common elements. So if, for example, one said you had to put your left hand over your right, and another said you had to put your right hand over your left, then obviously it was actually immaterial to the results, so I tossed it out.'

What he ended up with, was basically Vipassana lol, though he doesn't say that, and it's not exact. I guess it's really closer to Anapana which you do for the first couple days at the Goenka retreat too. Either way, I take that angle, and if anyone comes back after having done that for some time wanting to go deeper, I know exactly where to send them 😀