Not really sure what you think is wrong with karma? most of reddit's problem IMO come down to bad moderation.

But for comment scoring, there are really just 3 methods I've seen:

• Generic Up/Downvote - Reddit
• Categorized Up/Downvote - Slashdot - This worked on a technical forum to keep technical knowledge near the top, while still allowing stupid/funny comments further down the page, plus it made ignoring stupid/funny threads easy
• Personalized Up/Downvote - Facebook/Twitter/etc - basically build a profile of users you agree/interact with, and then weight their interactions accordingly to predict what content you'll like/hate.
  • I believe Ticktok take this to the next level, because 90% of users don't up/downvote, ticktok logs the passive act of continuing to watch content as a partial upvote making their algorithms train on the average users likes/dislikes faster.

You could probably combine Personalized & Categorized, but I've AFAIK not seen it done.

I think the problems with moderation are harder to solve, because you have both bad-faith moderators & good-faith but easily played moderators as problems, and you also want different dynamics as forums grow.

I think lemmy could really experiment with good moderation & meta-moderation and if the developers are interested anyway, be a far better forum as a result.

• Peer review of moderator decisions is something Slashdot did that went quite well. Once you'd been an active user with good "karma" for a while you would occasionally be asked to review other users votes, I think a similar thing could be done for moderation decisions
• Elected mods. For subs above a certain size, having moderation essentially boil down to whatever the guy who created the sub decides, is bad. I don't know exactly how it would work to prevent abuse, but as subs grow, at some point it would be good if the community chose the mods.
  • even short of full fledged democracy community approval of mod appointments would certainly reduce the amount of mod drama where it 1 bad head mod, will purge the other mods and replace them all with sock puppets.
• Users-led replacement of bad mods, similar to electing mods, it would be good for users to "recall" a bad mod.
• Transparency over mod actions, I understand that with the number of Nazis & other assorted trolls online reddit chose to let mods, moderate anonymously, but it really means you have no idea who is doing a good/bad job in many subreddits, some level of transparency for all but the worst content is key.
• Moving subs, as lemmy instances have some control over the content of the subs that reside on them, it would make sense for there to be some method for the users + mods of a sub to decide to move it to another instances. This not only prevents admin abuse, but also encourages competition between instances for technical administration & content administration.
• Splitting communities , sometimes subs grow "too big" and have different subcommunities that end up fighting for control of a sub, it would be good if there were a way of these communities splitting into 2 rather than fighting over the original name. not sure how it would work, but thinking about how r/trees & r/cannabis split or something similar. Maybe /r/canabis could become an combo of /r/canabisnews & /r/canabismemes, where users can just ubsub from the 1/2 of the content they don't want.
• Letting users weight subs/filter subs how much of subs they see, sometimes I've unsubbed from a high-content sub, just because while i liked the content it was overpowering the rest of my feed, it would be nice to have users configure how much of a sub they see (especially if combined with Categorized Up/Downvote), rather than complaining about "bad moderation" I can just personally choose to see less of what I don't want.

Anyway thank you for reading/not-reading my ted talk, but I suspect this will come up again so now I can copy/pasta it.