Telegram invented it's own crypto, without an audit it's untrustworthy. There's only Signal and Keybase that has been audited, so Whatsapp should be excluded from the list of trustworthy IM apps as well.
Whatsapp uses the exact same technology as Signal. If you consider that Signal is fine based on an audit of what is clearly an older version (do audits come out every day with new Signal releases? No, so the code you're running wasn't covered by the audit) then Whatsapp is fine based on being the same protocols with different branding.
An audited piece of software with relatively minor changes is definitely far more trustworthy than a piece of software that is much much more different. Whatsapp is garbage compared to Signal.
