This is cross-posted form the Romance Divas message board.
I write in both first person and third person. For me, it depends on what I want to convey in the story. If I want to show multiple character's viewpoints, I usually write in third. But if I want to limit my story to just one viewpoint, then I'll write in first.
For example, one of the young adult stories I'm working on is a romance and I wanted to include the heroine's, the hero's and the villain's points of view because I thought that would create more suspense for the story. Plus, I wouldn't have to rely on my heroine to resort to out-of-character ways for her to figure out if the hero is into her or not. Plus, my heroine has a supernatural ability that allows her to pass through the waking/real world and the dreamscape without realizing it and it sort of makes her crazy because she looses her grip on what's real and what's only a dram. But since I didn't want to confuse the reader with what's real and what's not, I can switch to another point of view, to someone who isn't going crazy.
In another young adult story I'm working on, my main character is completely obsessed over this guy. From her point of view, he's perfect. But I switch to other characters' points of view to show that he isn't as perfect as she makes him out to be, and that he could be a potential villain.
But the futuristic urban fantasy novel I'm working on is entirely in first person. My narrator thinks she knows about the world, but there's a lot of stuff that she doesn't know. So I can use her ignorance to show the world I've created to both her and the readers. Also, I felt if I told her story from multiple points of view that I would give away too much of the plot and take out that suspense element (which is the opposite of my young adult romance I mentioned above).
I also got started writing in first person because I had a difficult time with head hopping and never knowing whose point of view I was supposed to be in. By writing in first person, I could only write what this one character can see, hear, smell, touch, feel, do, etc. and I think it's helped me improve my writing. I'm equally comfortable writing and reading either third person or first person stories.
One of the other factors I keep in mind before deciding which point of view to write in is what genre I'm writing in. Most romances tend to be written in third person from the hero's and heroine's points of view, while urban fantasy tends to be written in first person. But then paranormal romance can be written in either, chick-lit is usually written in first, and science fiction romance can be in either, same with paranormal YA and mysteries.
I think the only point of view mesh up I don't particularly care for is multiple first person, where there are multiple point-of-view characters, but every one is narrated in first person. To me this creates what I call a campfire effect where everyone is sitting around a campfire, including the villain, recounting what happened to them. It annoys me because it just doesn't seem believable to me. But then I'm reading a story now that's in multiple first that doesn't bother me too much. The main problem I have is that all the characters' voices sound the same or at least very similar so it can be difficult to keep the different characters apart and tell which character's point of view I'm actually in. But then, I envy the author who can do multiple first really well because they manage to give each point-of-view character a distinct voice.