I like both lemmy and tildes, but i think lemmy is currently the best “batteries included” alternative, what i like about it:

• open source and under the AGPL, so no chance of it becoming purely proprietary, it can also be forked if it goes in a bad direction or some one wants to do something more innovating with the design.
• separates the counts of upvotes and downvotes, so if 300 people liked my post and upvoted it and 600 hated it and downvoted it i can still know 300 people liked it
• federated, disputes about moderation policies will probably happen, So if you don’t like it start your own instance and let the best moderator win, let the best moderation policy evolve naturally.
• mark replies as read manually just like email which is nice if you read a replay and return to it later.

what i like about tildes:

• has an exemplary tag you can give only once every 8 hours, i feel it encourages more high quality content
• it can show you new comments since your last visited
• it has a few large groups and you can’t add more but you can tag stuff, you can then treat a tag like a subreddit and see the top posts for a certain period of time (e.g. the highest voted posts this week tagged with “social media”). so you don’t have to start a small subreddit and then work hard to gain readers.

Stuff they both miss:

• the reddit ecosystem: RES is awesome, subreddit stats is also interesting.

advantage they both have (that not all other alternatives seem to have):

• sorting by top of week/month/whatever, useful if you visit just occasionally but looking for high quality stuff.