So when practicing mantra meditation (the only form of meditation I practice), should one be mentally reciting the mantras in a melodious way or in a monotonous way?

I ask this because I hear alot of people singing mantras on YouTube. They don't sing in a dramatic way that is akin to something made by a pop star but they are still melodious, kind of like how the Muslims recite the Quran.

That being said, the way the gnostic instructor recites mantras (such as the klim krishnaya govindaya mantra) was very non-melodious.

So... is it about personal preference? Does it not matter? By the way, thanks for all the support you instructors provide. Bless you