For the most part being a protagonist is a good thing.
However some protagonist may be bad people but they may also do good things when they come up against an antagonist.
A protagonist is usually the hero and is good but the protagonist can sometimes be a bad guy in a story as well.
An antagonist is the bad one and is an evil person so if you're an antagonist then you're not the good person and you do bad things.
The protagonist would be the one against the antagonist.
An antagonist is always the bad guy in a story so you don't want to be an antagonist but it's good to be a protagonist.