Feddit.online is another extremely well-established instance, with an absolutely enormous list of both Topic areas and Feeds available for use, yet it is located in the USA so may lack stability in the future.
Tangent: somehow even piefed.crust also has the "Newbie-friendly" label despite being explicitly a testing instance?
I see what you mean about piefed.zip though - federating with hexbear works against it, not as it being a good instance mind you but only it having received the "Newbie-friendly" label - yet it is the best compromise that can be found under the available circumstances.
Except PieFed.social itself, which is already to PieFed what Lemmy.World is to Lemmy in terms of centralization, which while not a concern now will be in the future. On the other hand, if the goal is to bring people from Reddit, then federation with hexbear might literally make recommending PieFed.social worthwhile despite that concentration effect, until some other instance is made that would work better?
Edit: apparently piefed.zip does block hexbear.net, lemmygrad.ml, and lemmynsfw.com to new users by default, sending them a DM explaining the reason for the choice and how to un-do, making seeing their highly controversial content as opt-in rather than opt-out. See the comment from @demigodrick@piefed.zip below for more details. This makes piefed.zip fully "Newbie-friendly", alongside piefed.social and others, and together with other aspects such as the long history of stability and responsiveness and deep experience of the admins, a solid choice for one of if not the most-recommendable go-to instance for new users.