Hi, I wanna know what is the most secure and best messaging app/platform...
Need an app that is crossplatform and has a very good numbers of features and security.
(And it has to be FLOSS)
I thought about XMPP clients, Signal, Session, IRC clients.. Propose and explain me your choice
There is no best, because none of them cover every use case or threat model. However, these are worth considering:
Matrix, if you don't mind minor meta-data leaks (reactions and avatars have not yet been moved to the encrypted channel, IIRC).
XMPP with OMEMO, if all your contacts are technically skilled enough to manage the requisite clients, servers, and protocol extensions, or if they have a skilled admin to do it for them.
Signal, if you don't mind linking a phone number to your account, can tolerate an ecosystem effectively married to Google, and accept the risks of a centralized service that can be attacked or shut down by someone with the right access or influence.
In situations where your safety depends on anonymity from the powerful or well-connected, I would instead look for a messaging system tailored for such things. (It would, of course, require giving up some convenient features that most of us expect from a general-purpose chat platform.)
Even with the UnifiedPush fork from F-Droid where you can avoid the Play Store & FSM notifications, you are still shackled to Android which isn’t a long-term solution with Google ultimately at the helm.
As far as I know you still need a phone number to create an account.
But for connecting you can use the new usernames (and make sure to disable automatic number sharing with contacts in the settings).
I used XMPP in the past, but long-lived public server support is almost nonexistent these days, and proper setup/maintenance requires too much tech skill for the general public. Also, it lacks modern features that many people have come to expect. I would only suggest it for small groups, and only if you can run your own server and provide tech support.
For my needs, Matrix is the best available today. It covers the things that I find most important, and is constantly improving.
For beginner self-hosters Snikket’s guide is even less work than others, but ejabberd/Prosody are easy to setup up compared to most software. General public is generally out at needing their own server even if the system requirements for XMPP incredibly minimal & many would have access to hosting at home on the cheap with dynamic DNS & basically anything with a processor + a Linux distro.
Not sure what the modern feature support you are talking about tho. Some clients already have stickers, reactions, threading… but the ‘X’ is for ‘extensible’ so it is all meant to be optional on purpose so it is easier to implement clients & democracy wins on features that clients decide are worthwhile to uptake (at least now that Google is out of the picture dictating too much)--& you have community-ran compliance suites for server features like the one for Conversations. Having used a couple of Matrix clients that aren’t Element, the fragmentation of client feature support is literally just as bad--except there is a lot less maturity due to age.