This can be a headache or a breeze for some, but really for me I think it goes down to one thing. How far does your scope go? Is the characters going to be present in all the important scenes? Or will they not be completely so?
As how big your scope is can decide how you are going to choose a point of view and whether your character is more than enough to narrate the story. If he or she is not, then consider third person limited, it offers almost the same closeness as first person, just in third person format. Third person limited is not just narrating through one characters point of view, you can switch if it’s necessary and far easier to do so in third than first, and if you want two narrators as there isn’t much of a need to have two separate voices, one would suffice.
While first person is limiting them to narrating through one person, hence the word ‘I’. It can be difficult if you have two narrators, you need to ensure that those two voices are distinct enough to tell the story and can be told from each other. Which even published authors struggle with, I haven’t really read a book which managed to make both the narrators even remotely different, they often sound the same.
Or if it’s really large, and sometimes you just don’t want to get that close to the characters and their perspectives, rather than seeing through their eyes. It is told from an all seeing narrator hence the name omniscient because the narrator here knows all, which can be quite hard to pull off seeing as you might need to keep a balance between keeping the narrator as truly omniscient and also not revealing too much to the reader.
As for me, I mostly write in third person, it’s just easier for me, even though I would extend to learning to write from first person with one book. But it’s mostly third, due to the nature where it tends to have characters which cannot be in all places at once. But I still want to have some intimacy with them, as such third person limited is the best choice for me, as it gives me the ability to switch if I want to, and also show worldbuilding as it’s not telling through the characters eye, and also allows me to be able to show a little voice here and there.
There are fewer limits with third person limited, than first person, where it’s just really through one characters eye and what the protagonist does not know, the protagonist cannot tell. As such, there are quite a few advantages to it, and despite what people say first person is hard, you have to keep in mind of their own knowledge and limits, and also the age of the narrator. It is almost impossible for a child narrator to be able to describe something well, they have plenty of limits even with great reading ability.
As such, mostly it’s up to you. Some writers prefer first, other prefers third, I just mostly prefer the latter, even though I would experiment with first in a future series, where it seems that first would suit it more than third.