Cloudflare and Google DNS are about the same in terms of real user speed. You won't notice the difference.
Cloudflare advertises more privacy and security and has different family options to block malware (1.1.1.2) and adult content (1.1.1.3) and they do claim that they're a few milliseconds faster than Google Public DNS. I have been using Cloudflare 1.1.1.1 on both IPv4 and IPv6 since it was launched. They do not send the EDNS Client Subnet Header (client's location to geolocate responses for services that use DNS-based load balancing) to authoritative servers. Very, very few websites would send bad results with Cloudflare DNS which will give an error, and that's the reason why. ECS can be used in DNS spoofing attacks and Cloudflare puts privacy as a promise in their service.
As for ad tracking, I did not notice a difference because I use Firefox which has Privacy Badger built into it which blocks ad trackers very smartly. I don't notice targeted ads on Firefox, but yes they do appear on Chrome. Ad tracking services usually use cookies, not a DNS resolver to target you. If a Public DNS is sharing your information with an ad service that's a bit alarming. However it's very important in net neutrality. An ISP's DNS resolver logs every single website you visit. If there are no local laws preventing it, it's so likely that they're using your data and selling it to ad companies like facebook. And they can use the data they collect to throttle services according to what is their policy on Net Neutrality.
Digicel supports regulation, Flow does not. DNS is not usually encrypted so any middle-man can see your requests it if they're looking. Cloudflare (and Firefox) forces DNS over HTTPS (DoH). Google is still working on it.
So all this to say that I trust Cloudflare's service over Google's and have been using it at the front end on my router since it was released. Cloudflare is also a major CDN and is a decent layer of extra cloud security before you access a website.
T&T Public DNS - Google vs Cloudflare
