I have used the Cloudflare service. I had an issue with their IPv4 -> IPv6 in their Dallas datacenter that got resolved after chatting with their CEO on Twitter

I have used the Cloudflare service. I had an issue with their IPv4 -> IPv6 in their Dallas datacenter that got resolved after chatting with their CEO on Twitter. Since then I have always also added an IPv4 fall-back as well. I can wholeheartedly recommend Cloudflare though :-)