1. Whichever trait you choose, it has to be "open" enough to go in several directions. For example, if your character has a "brave" trait, does this mean they are brave all the time? Are there some fears they really cannot face but because they are brave in other areas that hides this? Are they brave when out and about with friends but cowardly at home? Lots of directions you could go in there.
2. Whichever trait you choose, it should be something most people can identify with/aspire to. Most of us want to be decent, kind, brave etc. I love reading characters who have those traits and who overcome against all the odds. Instant reader sympathy.
3. Whichever good trait you choose for a character, they should also have a fault that goes against it, something they have to manage and control. (A good example of that is The Incredible Hulk! Mild mannered most of the time but boy when he becomes angry the sparks fly!). You have internal conflict here and also what happens when another character has seen the good side and suddenly comes to see the bad side for the first time? What are the reactions there?