In Europe, Whatsapp is ubiquitous. FB Messenger and iMessage are pretty rare here.
Edit: looks like I was wrong. I'm in the Netherlands. In the Netherlands and our neighbouring countries, Whatsapp is ubiquitous, so I presumed the rest of Europe was the same. I guess this proves that assumption is the mother of all failures.
I'd say >50% of smartphone users have Whatsapp in the UK and >50% of smartphone users have FB messenger, of course quite a few have both. I prefer Whatsapp, but contacting a small or large business like a pub or takeaway often works surprisingly well with FB.
Edit: looks like I was wrong. I'm in the Netherlands. In the Netherlands and our neighbouring countries, Whatsapp is ubiquitous, so I presumed the rest of Europe was the same. I guess this proves that assumption is the mother of all failures.