“Secure” NTP (NTS) sounds like a good idea and I guess if you’re already using CloudFlare on your hosts for stuff, then it makes sense to use them as a time server, but for the rest of us I don’t really quite see what would make me switch away from the public NTP pool
(But don’t get me wrong, I am continually impressed at how much cool shit CloudFlare offers for free. Hopefully they don’t eventually go down the Google path and start killing off things that are used by a lot of people 2-3 years from now.)
It’s a fun Raspberry Pi project to build your own GPS-trained private NTP server. I’ve done it, so my quick report is that I usually get within about a microsecond from GPS, and that my (albeit not great) internet connection uses time.apple.com as an upstream alternative, which lives usually within 12ms. Added Cloudflare just to see and they’re coasting right around a +/- of 30ms – not bad, but I’ll stick with Apple.