It really depends on the story, particularly whose story you’re trying to tell. Multiple characters can have arcs, but they don’t have to be the main-main character where the reader follows them around. Some stories are better off with us following a single character, others are better off with us following multiple. Single character stories tend to be written in first person, but there are, of course, many written in third. However, stories with multiple characters tend to be written in third because it is often written best in third as many who write multi-POV in first person don’t do it correctly and make it confusing or badly written (considering you have to make sure each person has a clear voice, and the majority don’t master this).
First decide what you’re going for as that can lead you into the next stage of picking.
When it comes to choosing how to tell your story, the next hurdle to jump over is figuring out what you focus on the most when it comes to distancing the character from the reader, or in other words, if your story is heavy with internal or external descriptions. Internal descriptions are where you pay closer attention to the thoughts and feelings of your main character, especially when it’s typical within the genre. For example, a lot of romances or contemporaries feature stories in first person because they often show more internal details. External descriptions, on the other hand, are the opposite; they showcase more of the settings, action, and so on, and even if they do feature snippets of the internal descriptions, it’s not the main focus. An example of this would be in fantasy and science fiction, where you tend to see a lot of stories with third person point of view because they’re focused on the external details.
Of course, this doesn’t mean you have to follow that. There are fantasies and science fictions in first person, and there are romances and contemporaries in third. However, there’s a reason why most follow the formula: some books just aren’t made for certain perspectives. I tried writing my YA sci-fi fantasy in first person the first time I tried to write it. Now yes, I was new to the genre and still improving on many aspects of my writing, but it didn’t work whatsoever. When I tried it the second time, many years later, I used third person, and that helped greatly. I can’t ever see it in first person now as third is best for it.
And finally, the next thing to think about is preference. Most writers tend to write their stories based on preference as some aren’t fans of first person, and some aren’t fans of third. But if you’re like me, whereas I don’t have a preference, you can either:
Base it off your stories needs. If you have a story with multiple characters and it’s within the historical fiction, action, fantasy, sci-fi, etc. type genres, you may want to go with third. If you have a story with a single character and it’s written within contemporary, romance, etc. type genres, you may want to go with first. If your story features a lot of internal descriptions, go with first person. If your story features a lot of external descriptions, go with third.
Pick from a hat. If you can’t make up your mind, maybe it’s best to write it down, place it in a bowl, and then choose with your eyes closed to see which you got. Whatever you get, you do.
Or you experiment. You can write a scene from the book in third and the same scene in first and see which you prefer the most. If you can’t make up your mind by then, it might be best to just choose a random one and go for it.
Another thing to think of, especially as you mention a mixture of each perspective, is how to sprinkle it in if it becomes needed. Adding first person to a predominantly third person story may seem a little weird, though it isn’t unheard of. But you may want to figure a reason why you choose to do that, like perhaps you only write first person when it comes to the villain or to an important side character that has a story-altering arc.
However, the popular choice is writing in first person for the main character the story follows and using third person for other characters.
At the end of the day, it’s up to you to decide, and how to do that depends on your story.