It depends on what you would like your Tamagotchi to grow up to become. For example, if you have an Ichigotchi and you want a Furawatchi, it would be best to choose Mr. Canvas to get the kindness points you need. If you just want a certain job, then you would choose a teacher for that specific job. Say if you wanted your Tamagotchi to become a scientist, you would choose Mr. Turtlepedia to gain the intelligence points you'll need to help with the job interview.