In a guy I look for: kindness toward people, animals, and the environment, ability to make me laugh and to think I am funny, responsible and not reckless (no smoking and no drinking excessively), understanding my problems
It can simply be someone receptive to me (listens), is genuinely polite, cares about me and has a good heart in general, has good morals, can have conversations and some similar interests, is giving and caring rather than scrutinizing and dogmatic. To be able to stand up for themselves while having a somewhat agreeable and positive attitude.
A girl thats naive, respectful to elders and loving the youngers. A girl that is mature and draws the line between opposite sex as she doesn't act close just gets the business done. A girl thats straight forward to other men but loving and childish to her man. A girl that is caring... so she can be the greatest mom. A girl that is smart basically and full of character. She doesn't try to attract men with her body rather her character stands out.
Differs for everyone. But for me? Hm. Sweet, affectionate, communicative, kind, loving, caring, understanding, good values/morals/principles, not easily corruptable/strong-willed, maybe a bit outdoorsey, trustworthy, loyal, classy, feminine... eco-friendly?
With the stuff I put, I might as well have said angelic or something equally as impossible to find.
The easiest way to explain it, for me anyway, is someone whose personality is compatible with mine. Everyone's different so a good personality differs from person to person. The general traits that seem to spread over most people are nice and caring.
I'm pretty sure that'd depend on the person, google "Personality Traits" and pick the obvious 'good' ones that society deems acceptable and redeemable. Like, "Loyal" or "Funny" for example. Avoid dripping your own bias into it if you can.