Most of the stuff I've written is in third person (non-omniscient) with multiple points of view (usually focused on 3-4 main characters and perhaps a couple of secondaries). It's a natural form for story-telling. And it's fun. It allows the author to craft scenes around the most effective perspective; it lets you change the "voice" of the writing from scene to scene; it gives you a chance to explore different characters more deeply. Maybe because it comes so naturally, and because it has so much utility, I've just gravitated toward 3rd person POV.
But twice I've ventured into first person POV for novels. The first one was based on a short story ("Don't Call Me Godless"), and I finished it about a year ago (I've been shopping it around for the past five months). The second one is my current work in progress. Here's what I've figured out about writing in 1st person.
It's a lot more organic. There's almost this sleight of hand you get to play with a first person POV, where you (hopefully) end up fooling the reader by pretending to be the narrator. The old saw, "show don't tell" just seems a little easier in the first person. I'll also say that for a discovery writer who constructs a good amount of plot structure during the writing process, 1st person POV is a much more straight-forward form. The story line has to be set around one set of eyes, from one experience, and, more or less, along one plot line. It's almost like you're putting together a recipe for a cookbook. So there's less wasted time on scenes, characters, etc. that end up getting cut later on.
But there's also a challenge that I've been struggling with. When you write a whole novel from one character's first person POV, you'd better like that character. A lot. Because you're going to be spending a lot of time with him or her. There's no taking a break from the main character in these kind of stories. If the main character's kind of flat, or dull, or annoying, or a trope, then it's going to be a long 12 months of writing.
Like all the choices that get made during the writing process, there are pros and cons to writing in the first person. I'm not sure it's something I'll do on a regular basis, but I do like the exercise of trying something different.