Signal considered the best between those 3 apps.

• Signal have E2EE. Facebook decided to copy the idea to Whatsapp. AFAIK, attackers have always gained access only by other methods.
• Telegram created their own protocol, MTProto. E2E is only enabled on private chats. By default private chat exist only on the device they were created on. So a lot of people don’t really use them.

So, in terms of encryption alone, Signal/Whatapp are safer.

I don’t know about you, but for me, the last company I’ll trust with my information is Facebook.

So if you can, use Signal.

If not, decide who you trust more. Telegram or Facebook.