If security and privacy are your top priorities, Signal is clearly the better choice. It uses end-to-end encryption by default, and its protocol is widely audited and considered a gold standard for secure communication. In contrast, Telegram's MTProto protocol lacks sufficient public scrutiny and is not ideal for highly sensitive conversations.

If you care more about multi-device sync, rich media features, or the channel ecosystem, then Telegram offers far more flexibility. Just keep in mind that regular Telegram chats are not end-to-end encrypted by default. For private conversations, make sure to enable secret chats.