I've used both.
Pihole is fine for a standard replacement of DNS for record lookups with the ad blocking most ppl want. But pihole is just fancy dnsmasq, you can't manage much more DNS than A records. (That was 4 years ago, though, things might have changed).
Technitium is a real DNS server with all the things DNS I supposed to be able to do. I use it for the zone transfers.
Performance is better than pihole, too, but that may also have changed.