I'm still put off by the sheer lack of comments on some communities like the main videos community on lemmy.world, where videos that'll have tens of thousands of comments on Reddit will have 100 votes, but 1-2 comments.
I miss a lot of niche subreddits like /r/HajimeNoIppo, /r/BJJ, and /r/IBS, but I can live without. What would be great is if the big communities had more engagement.
There also seems to be a lot of duplication of communities across instances. While I get the whole decentralised thing, it's pretty pointless to not have a mechanism to merge/join communities across instances that have the same topic. Why should lemmy.world and kbin have two competing pro-wrestling communities when neither gets a lot of posts/comments?