Depends, imo.
Writing a likable protagonist requires you to make them human. Likable protagonists are likable because of the way we’re able to relate and empathize with them. So, in that strain, creating a (mostly) universally liked character is a tough go because you have to make them realistic.
Why, with writing a sociopathic protagonist, you could essentially do anything. You could make their backstory brutal, tragic, have their motivations aligned, etc. But doing this doesn’t mean you’re writing a good sociopathic protagonist.
If you were to write a well-researched and psychologically layered sociopathic protagonist, I’d say that they’re a lot tougher to write about because of the amount of research and thought that goes into that character. Not only is psychopathy as a whole heavily stigmatized against and misunderstood, but it’s a complex psychological state of mind that has many layers. Many usually have their own set of moralities/rules, even if these moralities/rules don’t align with society. More importantly, why we all face antagonists in our lives, many don’t actually have a good example of what a sociopathic human-being is like in your day-to-day, so many are working based soley off of research and some experience.
Why, if you were to write a well-researched protagonist who is more likable, there’s more life-experiences and people in our lives we’re able to take inspiration from. On top of this, we have many issues ourselves, and in the people around us, that we can find relatable. A protagonist who is well-liked but suffers from depression is hard to write because you have to research that, but meeting someone like this or being this type of person is far more common.
So, in conclusion: If you’re going to write a solid, well-rounded “sociopathic” character then it’s going to take a lot more time, consideration, and effort then if you write a relatable likable character.
Ofc, this is all generalizations. Our life experiences give us many different perspectives, so for some writing one or the other may be easier depending on their own backgrounds, studies, and situations.