From the TROID publication: Upright Moral Character by Shaykh Muḥammad ibn Ṣāliḥ al-ʿUthaymīn (translated by Mūsá Richardson)

There is an issue worthy of discussion here: Who is more virtuous – someone who has commendable character naturally, or someone who worked to attain it? Which of them has a higher status and more reward than the other?

We reply to this question, saying: Certainly, the person created with good manners is more complete with regards to his behavior, and with regards to the actual presence of the manners within him. That is because he does not need to struggle or overcome any difficulty in manifesting them, nor are these manners absent in certain situations and scenarios since they are found within his natural disposition. Whenever and wherever you meet such a person, you find him having good manners, no matter what the situation. So, from this angle, he is more complete without doubt.

As for the one who struggles, refines himself, and attains good manners, then he is certainly to be rewarded for this, due to his personal struggle. However, he is much more deficient than the other when it comes to the completeness of his character.

Furthermore, if a man is granted both types, some good character naturally and some attained, then this is the most complete case. The types of people in this regard are four:

1. One who has been deprived of (innate) good manners (and he has not attained them)
2. One who has some (innate good manners), but has not worked to attain any more
3. One who has good manners naturally and has worked to improve them
4. One who has been deprived of innate good manners, but has worked to attain them

In conclusion, the one who has good manners naturally is more complete (in his character). However, when a person struggles and endures hardships to attain good character he will be rewarded for his efforts.