I prefer 1st person because it's seeing through the eyes of the player. 3rd person has it's uses and some games are better using it.
Halo uses 3rd person for vehicles and turrets. It's a good example of it's use in balance with the rest of the game.
However, games using both perspectives can go further. The best option is to allow both options, with balancing facts. In Real Life, you cannot see in the third person unless you have a Heads Up Display (HUD) and a mobile camera. With 3rd person, you can often look around objects without revealing yourself. So to balance a game that uses both 1st and 3rd, you may have 3rd person cost an upgrade spot, make it vulnerable with a bit of a tell, which is to say you can see their flying 3rd person camera and possibly disrupt, damage, or shoot it down. You may also grant abilities to either perspective. 1st person may in general be more mobile and agile, and 3rd person may send their camera to scout a position.
I can't wait for a decent game that uses these ideals and more.
