Almost nobody is the better answer. Most people use whatever their ISP, phone, or browser provides.
Is the ISP-provided router a self-hosted recursive DNS server?
No, via dhcp it points at the ISPs caching servers.
Well, I'm doing that, and in this case, Cloudflare 'protects' the website and blocks it (based on my Belgian IP). So no matter what DNS I use, it see "Unavailable For Legal Reasons".