Since Animal Crossing mobile is not available yet, how to choose your town in Animal Crossing: New Leaf is mentioned here as a reference.
In the Animal Crossing games, players are able to pick their favorite map layouts. Some of them are particular about the their town layouts and restart the game until they get ideal town layouts since those layouts are randomly generated at the beginning of the game.
How to pick a town layout
In Animal Crossing: New Leaf, you are asked to choose one town layout from four of them that Rover shows you once you decide your name → Tips for naming in Animal Crossing mobile.
Symbols
Villager houses
Town Hall
Re-Tail
Plaza
Train Station
Example maps
Changes of your town
As you make progress in the game, your town will have more facilities, villagers, and their houses.
What are the best town layouts?
There is no general condition for the best town to be honest. Everyone has his/her own view of town layouts. If you however want to take others' opinion into consideration, see the followings:
Re-Tail locates nearby the center of the town at the best, since it is a place players visit most frequently.
A town with villagers' houses locate close to each other is better than that with villagers' houses scattered about. That lets you easily visit villagers' houses.