Belgium here. I don't have WhatsApp, Messenger, or any social network account.
I only use Signal. Most of my contacts are on Signal (meaning people from work or close friends/family). I would say ballpark 85%+. My shrink and MD are on Signal. I'm lucky enough to work for an organisation that promote and emphasis privacy and security. I'm also quite a good evangelist to my family and few friends ;-)
Once I step out of that circle/bubble of people, I realize how peculiar my situation is, mind you. I have 2 teenagers and sometimes I have to communicate with "regular" people.
EDIT : in that case, I use regular email, SMS or phone calls.
WhatsApp is widely used in Belgium, as is Messenger. My wife tried to remove WhatsApp at some point, but that made her social life too difficult.
Netherlands here. 80 contacts on my phone. 20 on Signal, of which 10 are quite normal people. Almost all 80 are on Whatsapp. No idea about Telegram.