But with Signal you still need a smartphone (i.e: very bad for privacy); while with telegram you don't. Also, with Telegram you can protect the account with a password, so you can use a burner phone, literally once, and then forget about it.
With Telegram you have no privacy - no one uses the e2ee (secret chats). Perhaps because the desktop client doesn't support the feature, and even if it did, secret chats wouldn't sync across devices.
While Signal's QR code pairing method is more awkward than Telegram's SMS one, it also prevents your account from getting hacked remotely in Iran by stealing your SMS messages: https://securityaffairs.co/wordpress/49976/intelligence/tele...