i've used some of those as well, and finally settled on adguard pro for my ios devices. do you (or anyone else) know how nextdns and adgaurd compare on ios?
adguard pro allows customization of dns servers (including DoT), has a running local log of dns queries, and provides custom whitelists/blacklists functionality. their dns (or maybe the app) very occasionally hangs requests, making my device seem like it's disconnected.
i've considered switching to nextdns but haven't found a compelling reason yet.