Which is more sinful – shaving the beard completely or trimming some parts of it and leaving parts?

Shaykh Amad al-Najmī:

Without a doubt, shaving it completely is more sinful and it is even more sinful for an individual to shave his beard and leave his moustache [to grow]. This is more sinful, [sometimes] you find a person’s moustache, he leaves it to grow and shaves his beard every day.