meh, 5, I have found it largely 50/50 and one should not engage in kindness with the expectation of a return

LMAO NO. 1

50%? many people do respond kindness with kindness who would otherwise remain neutral, or worse, be rude. working in customer service, i’ve definitely seen this. but of course it is not true for every person you come across- you can still be met with neutrality or worse

I'm not really sure. But I do know that if it's more than about, say, 20% true, it has to be the result of a mystical force like karma, the threefold law, or the law of attraction. And I think there are plenty of people who are genuinely kind people who consistently suffer at the hands of others, often because they're good people. And if it's that way for them now, it probably will continue to be that way for them. If there is a significant degree to which kindness comes back to you, it probably doesn't happen within the current lifetime. But then, why would it be any likely to happen later?

As a scumbagdad fan, I'd say 1

If only that were a law of physics ! But it will come back to you, though often not in a way you had hoped. So I got a firm 5 for you. ;-)