XMPP (with omemeo) is the classic (and also what FB messenger uses behind the scenes, without omemo), Matrix is the new kid on the block taking over. Both are decentralized sorta like the fediverse (but separate from said fediverse.)
Used to use Signal, but they’re removing SMS support so everyone might as well switch to matrix. Wickr was bought by amazon (and they say they won’t ruin it, riiiight), so that’s out. Idk enough about briar or session, and telegram isn’t as secure as people seem to think.
Yeah that is annoying as hell. Like I get it if it’s just like “my files are private, I’ll open them if you have shares” but that whole “I need X album FLAC and a $50 baskin robbins gift card and then I might share with you” shit is the lamest thing I’ve ever seen.