How to choose
If you mainly like making characters, start with Miitopia or Fashion Dreamer. If you like a daily island rhythm, Animal Crossing is a closer fit.
If you like the strange, cozy, low-pressure side of Tomodachi Life, smaller creative games such as Ooblets, Calico, or Sticky Business may scratch part of that itch.
What no alternative fully replaces
Tomodachi Life is unusual because the appeal comes from watching customized residents act out surprising social scenes. Most alternatives match one piece of that formula, not all of it.
FAQ
What is the closest game to Tomodachi Life?
Miitopia is the closest Mii-focused comparison, but it is more of a role-playing game than an island life simulator.
Is Animal Crossing like Tomodachi Life?
It overlaps on cozy daily routines and island/community customization, but it does not focus on autonomous Mii social drama in the same way.
Are there PC games like Tomodachi Life?
Some PC games match parts of the cozy or customization appeal, but there is no exact official Tomodachi Life equivalent on PC.