Someone I can talk with and share anything with and know I won’t be judged or have it shared amongst others. Usual things like funny, good personality. But I think there has to be at least some sort of attraction there. You don’t walk past a (how should I put this….) not-very-good-looking person and think “they aren’t good to look at, they must have an amazing personality.”
The person may not tick all the boxes of some dream-person you’ve created (type, I guess most people would say) but they work for you.
(all this from very little experience, but from learning from others)