Personality is #2 for me. #1 is just if the content is relevant. This could mean i sub to someone for a year and unsub. or 6 months. or forever. I follow youtubers who create content that pertains to me at that moment in life. Gamers? probably always. Interior design? im big on it right now since i moved into a new apartment, but prob wont be in a year. That's why i actually like youtubers who do a variety of content, because if ive moved on from content A but they also provide content B, ill stay subbed.