So, I don't think there is one. At least not one compatible with democratic-like systems.

The fundamental issue here, at least to me, is that the upvote is an "I like this" signal. The instinctive use of an upvote is to see more of what you like. Turns out that what people like is what people already agree with.

Unless you build a strong culture that values the signal/noise ratio (remember that early reddit had much more of "UPVOTE IS NOT A DISAGREE" culture, hivemindy as it was), you're not getting your desired outcome. Worse, if you let in the mobs, it doesn't matter how principled your initial group was as they'll soon be overwhelmed by the crowd. The historical record there is obvious.

I think the only way about this is gate-keeping. You want that culture, you'd better enforce it. If you somehow start with a seed userbase of principled people, you only allow people voting rights once they meet whatever gatekeeping criteria that you've set. I don't think this is that scalable, but smaller more tightly knit communities might be a plus to some.

Actually, I'm wondering if something like this might have a niche out there somewhere. We know that Digg in the old days had the superuser group, and the strength of reddit was it's specialized subreddits. Would a system crossing specialized subs with hierarchical user privileges (viewer/voter/voter_with_grant_privs) be something that could work?

The fundamental problem is that people will treat upvotes as agreement, even in communities who set out to make sure this isn't the case. I stopped posting at tildes.net recently, which has this exact problem with upvotes in spite of this being a cultural pain point that caused so many of tildes' users to leave reddit.

In a way it's sort of evolutionary. People attempt to propagate their own ideas or similar, and remove ideas they dislike from the meme pool, via voting systems.