DoH is actually a very cool technology. Many people already ditch their ISP's DNS servers because they are unreliable. What do they replace them with? 188.8.131.52 or whatever the Cisco/OpenDNS ones are. But there is still huge scope for manipulation and interference of any unsecured DNS queries, regardless of who your resolver is. Using dnscrypt makes things slightly trickier for snooping but you're still putting trust on whoever runs the proxy.
DNS over HTTPS means your ISP and anyone else in the path is not able to see your DNS lookups. and would bring some speed gains by re-using/multiplexing HTTP/2 connections.
Considering that a decent chunk of many sites are already served by Cloudflare's CDN, and in many cases people are already putting regular DNS lookups through Google/Cisco, I don't have much of an issue with this in terms of privacy. You've already opted-in to the Nightly builds (and all its telemetry) so being opted-in to further studies within the browser is sort of expected I would guess.