All the comments from all cross posts on a single page is great. You can also add your own user flair like you could on Reddit, which lemmy doesn’t support. I haven’t messed with it much yet, but the ability to make lists of communities into feeds also seems really useful.

I haven't used piefed myself but I wouldn't want to switch to it because I feel like it gives more power to downvotes and karma (or "reputation" as they call it):

• Comments with -10 score are collapsed by default.
• People who get downvoted a lot end up with a ‘low reputation’ indicator next to their name. You’ll know it when you see it.
• Upvotes in meme communities do not add to reputation.

Those are three of the twelve points listed as differences to lemmy on their features page.

I also don't agree with some of the points in their article on "PieFed features for growing healthy communities".

I asked that question recently and got some helpful responses,

https://lemmy.world/post/30977919

tl;dr PieFed has different people behind it, a few more features, and is written in Python instead of Rust (I'm not a coder or an instance host, so don't ask me what that distinction means, but I've anecdotally seen more people saying python is easier to work with than rust than the other way around),

PieFed communities federate with Lemmy communities, tho, so no matter which kind of instance you're going through as a user you should be able to interact with all the communities (assuming your instance admins haven't decided to defederate with the other instance for some reason)