Which DNS service do you use and why? Is it more for security or speed or both? I usually use Google DNS. But use OpenDNS occasionally.
Dns.Watch on PC and Adguard (dnscrypt) in browser. I wanted to use Yandex Family, but Yandex browser does not let me to pick it, though it offers multiple versions of adguard, opendns.
My own adblocking, threat blocking black hole DNS server, a smart DNS service to spoof geolocation and several DNS servers that are provided by the VPN services I use. Setting up a recursive DNS server is a nice Linux project that gets you right into the back end of the Internet and ends your dependence on 3rd party servers. A VPS server that can handle it is pretty minimal and costs just a few dollars a year. For speed, I set up a a caching forwarding server on a Raspberry Pi on my LAN. Query latency is reduced from several hundred milliseconds to around 8 once it is cached in the Pi.
Personally, I use these two https://dns.seby.io/ https://dnscrypt.me:8443/ In computer, DNS is set via SimpleDNSCrypt, in Android via Adguard DNSCrypt. These two scores pretty good in GRC DNS Spoofability test. External Ping and Query both are ignored, DNSSEC and very good entropy.
It's obviously not 2017 anymore but I just switched back to Quad9. I dropped them in the past after an extended outage but it seems to run pretty well now. It seems a little faster than the 1.1.1.1 we had been using.
I've been using Quad9 for about 2 mo. and find it reliable. (I actually felt Cloudflare DNS was faster, but I don't trust the company enough to use it.)
Cloudflare was faster for us in the past but they are not as fast as they once were and Quad9 is faster than it used to be. Of course this could vary by location. I'd still prefer to use Quad9 for other reasons. The fact that they block malicious domains being the biggest reason.
Security Filter here: https://cleanbrowsing.org/ I have tried Quad9 but my ISP prevents me accessing the Australian servers for some reason, meaning I connect to the West Coast of USA.