Both certainly have their merits, I won't deny that. I don't have time to get in depth right now, but I'll give a very general opinion.
Third person allows for a little bit more freedom. You can swap character point of view easily and follow events that the narrator in a first person event wouldn't have any knowledge of. Basically, it can be a bit easier to get inside more heads.
First person I have felt can be limiting. To some degree, depending on the genre of course, I find first person perspective less dramatic. No matter how badly the character gets beaten, or threatened, or whatever happens, you know the character is going to live or else how do they tell the tale? Now as I said, it depends on the genre. Involve a character in a world of magic and actual gods roaming the earth then it is possible for a character to die and still keep the tale going. However, set the story in the year 2010 in a world identical to our own, well, death is permanent, therefore I feel it is less dramatic. Sometimes first person can also limit the amount of heads you can tell the story from as sometimes it can confuse the reader. If you're sticking with one head then first person works quite well as long as you remember your narrator can only speculate as to what is going on in someone else's head and not actually know (unless of course the genre allows it lol).
I'm sure someone more eloquent than myself will stop by shortly and give you a better idea.
Though most of all, I support whichever perspective you feel the most comfortable with.
Perhaps try writing the same scene in each way and see which works best for you. If all else fails, write a chapter or two of the story from both perspectives to judge and even let a beta reader take a look at it.