Depends a lot on who you're talking to, and your, and their threat models. For many, signal provides pretty good protection, which brings us to a salient point, anything that actually provides good security will attract plenty of negativity, often from state level actors who feel (are) threatened. If you're playing at that level, adam_y is right, dead drops and one time pads. Presuming lesser threat, signal beats telegram and FB etc. Email is plaintext unless proton to proton, encrypted email is fine (look at PGP) and indeed if you encrypt at home before sending it's pretty much a dead drop anyway, as long as the other party has a key, and I'm wandering off the beaten path.

Seems you want a secure messenger that works and are scared by random crap because you don't have the relevant knowledge to decide (spoiler, very few do, and it's insider knowledge, the world is imperfect), fair enough, but don't let perfect be the enemy of good. As long as you're willing to give up your phone number, Signal is well regarded (exchange privacy for security, you decide). But yeah, no perfects, world imperfect, trust hard, deal ;)