That is actually a great question. (insert huge disclaimer here that this is my personal opinion). I believe that if the right people were to build a DNS resolver at a ISP of sufficient size/ diversity, using the right tools, they would be unbeatable by Cloudflare (in region) in terms of performance (insert variety of reasons which can be reasonably deduced and some more esoteric here).
If you look at DNSperf.com you will see that in some regions we aren’t the fastest today (although since some of my team tracks this more closely than their glucose levels, we are making massive improvements). But what we’re doing isn’t magic per se… not to say it isn’t sufficiently advanced that even to me it seems like magic… . but you get the point.
I think it is very likely we will expand in the UK in the near future and that there is a chance that could improve our numbers vs. what you see on BT. But I sincerely hope (and I see evidence already this is happening) that our efforts actually incent other resolvers to improve their performance as well. And, many of these changes also have trickle on improvement effects for Cloudflare customers which is an obvious additional win.
But stepping back for a moment, I think our pledge re: privacy is a sincere one and your ISP may be just as resolute in that regard (if so, I applaud them). If it turns out that in (region) (under circumstance) someone provides better performance on all the measures that matter to you… I consider that a win for Cloudflare (and more importantly for you).
When I interviewed Cloudflare, @eastdakota told me that our mission was to ‘build a better internet’. It sounds cheesy, but honestly that’s what I show up to work for. If that means others up-level their game so we aren’t #1, I am actually ok with that. We’ll catch them tomorrow.