The best ones use the person's name and a line that sounds like them. For a partner: their name and a pet name, sung as Romantic R&B. For a parent: "Mom is calling, pick it up", as a Gospel Choir. For a friend: an inside joke over Drill or Phonk. For work: something calm, like Lo-Fi Chill, so the call does not make you jump.
Keep the line short and easy to hear. Ringoz sings lines like these in twelve styles, and suggests a line if you are stuck.
Related questions
How can I make a personalized ringtone as a gift?
Make a ringtone with their name and an inside joke, then send them the audio file.
How do I make a ringtone with someone's name?
Make a short clip with their name in it, then assign it to their contact.
How can I make a ringtone with my name in it?
Record or generate audio that says your name, or use an app that sings it.