According to The Oxford Dictionary,
Nepotism is the practice among those with power or influence of favouring relatives, friends, or associates, especially by giving them jobs.
Cronyism is the appointment of friends and associates to positions of authority, without proper regard to their qualifications.
The keyword that differentiates between these two word is “qualification”, if you favour someone over another and both of them are qualified for the job then you should use the word nepotism. If however you still favour someone even though they are less qualified then that is cronyism.
Now let’s rethink your word choice.