Signal is an interesting case study in UX failure. I and a bunch of other tech forward people were on it in its heyday but after they removed SMS support and implemented shitty UX like that nag dialog: Neither I nor a single person I know uses it any more. Everyone is on Whatsapp or iMessage.
It may be cryptographically superior, but does that matter at the end of the day if nobody uses it?
Cryptographical superiority aside, Signal doesn't collect personal data, unlike Whatsapp. For me that's the main reason to use it. The UX is good enough, although some points can for sure be improved.
Whatsapp should be a non starter. What Mark Zuckerberg did to Whatsapp should be required reading for anyone using the internet, and then decide if you still want to use Facebook (never mind, they build a shadow profile for you anyway)
A few of my neighbors have kids the same age as my kids, they're on a WhatsApp group chat, and my choice is either use WhatsApp or make my kid miss out on social events, so it's not really a choice.
"Hey let's switch to this app that nobody else is using and it sends you annoying popups every month but trust me bro it's more secure" is not a winning argument
It may be cryptographically superior, but does that matter at the end of the day if nobody uses it?