Given that sunaurus has explicitly declined to defederate from unpopular and highly-blocked instances, stating that disliking content is not a reason to invoke defederation, I'd have to say this is the least-censoring instance I'm aware of. At least at the admin level.
At the community level, communities can moderate and censor themselves however they like, but I certainly can't think of any examples I'd call censor-heavy.
Less here than any other instance I've noticed. It's why I like this instance. World, ml, beehaw, and hexbear all use defederation and banning at the drop of a hat. They're all trying to cultivate specific identities for their instances, so I don't begrudge them for it exactly, but it's not for me. I like the lack of censorship here and the openness. It makes the instance generic, but in a cool way. It's like the Union Station for the fediverse, or a skeleton key. If a user doesn't like a corner of the fediverse, they can block it themselves now, from individual users to whole instances. Sh.itjust.works might be like it, too, I haven't looked too much into their policies.
It's enough to make me realize I should donate to this place more lol.
Lemm.ee tends to have communities more focused on hobbies. The real censorship happnes for communities where things can get pretty heavy and conflicting. Like politics. Most of that is on .ml, hexbear, and .world in my experience.
I find it difficult to keep track of instances since I always browse "all". The hivemind works as expected (if mass downvoted unpopular opinions can be called censorship). I've had a comment with the mere mention of China in a somewhat negative way, deleted pretty quickly (but don't know if it was in this instance). Haven't noticed much else.