I use NextDNS since 2021, after a frustrating experience with Pi-Hole in a Raspberry Pi 3b (system broke by itself every other month, I think because faulty SD cards).
NextDNS is so good, and their free tier so generous, that sometimes I feel bad for not having to pay for it. Can’t recommend enough.
I dont have actual data to back it up, but out of the DNS services, ad-blocking or not. I feel NextDNS has the fastest DNS Network. And it is very consistent.
To the point I wish NextDNS would start offering Managed DNS services like Amazon Route 53 or DnsMadeEasy.