Starting to explore AI companions. What would you recommend?

I've mostly used AI for productivity but recently got curious about AI companions.

There seem to be a lot of options out there, and I'm not really sure what separates a good one from a bad one.

For people who've been using them for a while:

• What made you stick with your current one?
• What's the biggest feature people overlook?
• What do you wish you knew before starting?

Curious to hear some real experiences.