I've tried Mastadon and Matrix (using Element). I think they're two of the best examples. But I think for none of these have quite nailed the UX of existing social networks (Mastadon's not quite as good as Twitter and Element is not as feature-rich as Discord). I really think it's as much of a UX problem as a technology problem and not enough decentralized projects have top-tier UX and UI talent to compete.

Mirror (https://mirror.xyz/) is an interesting Web3 alternative to Medium. I think they have gotten a lot of the elements right. Blog posts are backed up to Arweave perma-storage and they have easy point and click integration for crypto donations (with automatic splitting for multiple authors), NFT auctions, and crowdfunding.

At any rate, I think decentralized social networks are still nascent and we haven't yet seen a break out success on the level of Discord or Twitter or Facebook, but I remain optimistic that it will come.