Most security experts who actually know what they are talking about do recommend Signal for most users, including [https://twitter.com/Snowden/status/661313394906161152](Edward Snowden), [https://www.schneier.com/blog/archives/2018/06/russian_censors.html] (Bruce Schneier) and [https://linktr.ee/glenngreenwald](Glenn Greenwald). Eveyone should consider whether they would rather follow the advise of people who have literally fought the NSA and read the entire Snowden documents or belive in the FUD spread by some people here.

All decentralized protocols have this issue. The servers need to handle metadata for chat groups, like who is part of which group. If the servers are under individual control, nobody can force them to delete this data. The question is, do you trust a non profit organisation like signal to minimize and delete metadata (which court orders have proven they do) or do you trust all individuals of a group chat to do the same when you manually ask them to.

Matrix is the worst option when it comes to avoiding metadata. A group chat with users on 10 different servers will create ten different places to store the metadata with no way for any user to delete or edit this metadata. Its a privacy nightmare.