It's essentially the same question as "why would you choose another DNS server?" There are numerous other options like Google, Quad9, OpenDNS, OpenNIC, DNSWatc

It's essentially the same question as "why would you choose another DNS server?" There are numerous other options like Google, Quad9, OpenDNS, OpenNIC, DNSWatch or Verisign, each of which have pros and cons like speed, privacy, reliability or accuracy. Many people also use VPNs which provide DNS servers that are perceived to increase privacy. I know this is currently US only but were it to roll out worldwide, personally I'm in a country with strong legal privacy protections and trust my ISP far more than any American company.