I am going to repeat what I have said for another similar post.

I still stand for Signal App.

• Telegram has no default E2EE, Telegram is run by for profit company
• Multiple flaws were found in Telegram’s encryption algorithm
• Almost all cleartext messages are stored on telegram server, but signal stores encrypted message temporarily
• Signal is non-profit & all their source code + finances are public. Even their server codes are publically available