By default, voters rate candidates out of 5 stars.
People are exposed daily to this type of rating in reviews of restaurants and movies, hotels and phone apps.
The familiarity helps voters understand how the ballot works without verbose explanation.
Unfortunately, elections with 6 or more candidates force the expression of indifference between 2 or more candidates;
There simply aren't enough unique options to go around.
In cases where your election has a large number of candidates, an unambiguous dropdown may be preferrable.
Be aware that voting out of 5 stars provides the benefit of familiarity.
Your voters may well be confused if presented with more options.