What is wrong with telegram?

Hello everyone. I use telegram everyday and for everything and I always thought of it like a private messaging app (especially compared to whatsapp). But I’ve seen many times that in this subreddit telegram is getting a bit of hate compared to wire or signal which are getting love. Also what about wickr? Isn’t it good either? ( https://www.securemessagingapps.com/ this site says it is)

Thanks to anyone who will care to explain me and answer all my questions

Found here