I asked you a very specific question, what makes a good character for you. Forget Nami and Sakara for a moment. Let us first define what a good character is for you.
But first and foremost, for a character to be interesting, you have to remember this character properly, of course in positive manners. I will always remember Sakutrash but it is not because she is good but because she's that bad. Furthermore, this character has to be interesting, having a more individual personality, not being bland and boring and the most important thing: not being forgettable. JJK is a cool manga but I am not satisfied with the characters besides Gojo and Sukuna. Most of them are average and easily forgettable - I don't even remember the name of the MAIN CHARACTER. He's just uninteresting. Characters are important and they have to impact you even after you've already finished watching/reading the anime/manga for a longer time.
Now you can clearly see some of my ideas and thoughts about good and bad characters.