I would say the biggest example is social democracy. There is no denying it brings great improvements to quality of life and general happiness. They are obviously not enough to us radicals, but they do exist. Greater healthcare, greater education, greater prison systems, less homelessness, etc etc etc. But we of course know the dark side of all of that. The colonialism and "soft power" behind it. We know that, because it is still ultimately capitalism, it doesn't eradicate the misery, it just hides it away. It makes other people have it instead of them. And we also know all of those nice things are merely concessions given by the ruling class that can easily be taken away at any time. Thus, if such a system brings improvements through means like those, I don't care how great the improvements are, I don't support that system.

We can also use what I'm saying to refute the fascists who say "oh, at least the trains came on time" "oh, at least everyone had a house" "oh, at least there was less crime". Rather than going into the long and most probably ultimately pointless task of proving none of those things were historically true to the person saying them, I prefer to simply say "I don't care. Even if that was true, if it was achieved with fascism I don't want it."