NextDNS vs Pi-hole
Both block ads and trackers at the DNS level. One is a $2/month service; the other is free forever on a $35 Pi. They actually compose nicely.
NextDNS — DNS-as-a-service. Per-device profiles, detailed analytics (opt-in), DNS-over-HTTPS / TLS / QUIC support, works on cellular. Free tier covers 300K queries/month — enough for most personal use. Paid is $2/month for unlimited.
Pi-hole — self-hosted on a Raspberry Pi or Linux box. Network-wide for everyone on your LAN, including IoT and smart TVs that NextDNS can't easily configure. Free forever. Doesn't follow you off Wi-Fi.
Pick NextDNS if you want set-and-forget filtering that travels with you on cellular. The cheap paid tier is the right answer for most people.
Pick Pi-hole if you have a home network with smart TVs, set-top boxes, or IoT devices you can't reconfigure. The network-wide model catches devices you can't install software on.
Best move: both. Pi-hole at home for blanket coverage. NextDNS on laptops and phones for when you leave the house. Configure phones to fall back to NextDNS when not on home Wi-Fi. Total cost: ~$35 for the Pi + $24/year for NextDNS premium = ~$60 in year 1, $24/year after.