It depends on the way you view things. (pun intended) I personally think both ways are as good as one another. With third person, it gives you the ability to see to your sides like with your peripheral vision in real life. With first person it gives you a more direct view of what's going on. It also depends on the game, or the different aspects or characters of the game.
For instance, in Star Wars: Battlefront, I prefer first person for all units except for the Republic Jet Trooper and the Imperial Dark Trooper. With their jump jets and jetpacks you need the extra vision for better control and to land on tight spaces, like the points on the Spire in Geonosis. But with more realistic warfare type games, like MoH or CoD first person gives you more perspective in tight or cramped underground maps.
I like 3rd person view better. If you play a game that has you upgrade your armor or weapons, I want to be able to see it to show my achievements of getting to that point of time to be able to upgrade it.
