It's a hard question to answer because I think everyone has tidbits and experiences that you can learn from, and that interests me. Frankly, most people have interesting qualities, if you're curious enough. Sometimes you have to dig to find those qualities.

Generally, I tend to favour users who have multiple interests, who engage in a hobby, who share insightful things, who are interested in interacting rather than just preaching to the void. But also users who are just kind works for me. It varies. Not a useful answer, I guess.