Another anecdotal UK experience: all contact with humans is via WhatsApp except one older relative. My SMS inbox is 99% 2FA codes, appointment reminders and delivery updates
For me its whatsapp for everyone under 90 (over 90 is email or phone) and signal for everyone who is in IT or is close to someone IT. With the caveat that as almost all signal users are on WhatsApp too sometimes we forget and use it anyway.
Sms is mostly for when you want to add urgency and be less likely to be muted.
I would love to get rid of WhatsApp due to FB and hope to do so somehow soon.
