I really like the block all apps by default. I read release notes, download something, scan with App Manager. If that’s all good then it can connect to the internet.
And I use the Wikipedia app so I can block intake-analytics.wikimedia.org and the app still works.
I don’t have any experience with AhaDNS Blitz.
With RethinkDNS I have had occasional failures on their Max resolver, changing to Sky then works. That has only happened two times though, and was fixed with a few hours.
Sorry I can’t be more help.