Signal and Telegram are on the edge. I lack enough info, but from the recent interview with Pavel Durov I believe Telegram does have a degree of censorship/moderation. More importantly the company had to exit Russia end the US to remain relatively free... but that is unlikely to last long term. Since it's not FOSS, we cannot know ho much surveillance it has.

Signal is run by a foundation, but again there are many doubts about how private it is.