the last GTA game I've played was GTA 3 when I was like 8

I disagree with first-person being more immersive; it doesn't "put you in to the game," because it doesn't simulate first-person vision accurately (It looks all "flat," instead of "spherical," as our vision is; in addition, it doesn't take in to account peripheral vision (You don't gradually lose detail toward the left, top and bottom of your vision as in real life), and plus you're still usually sitting a ways away from your television screen) and you can miss alot of environmental details in first-person perspective (Let's say you're in a car chase and drive by some funny billboards or something; you only see what's directly in front of you, as opposed to what surrounds you),
Long-story short: third-person perspective will always be the superior presentation format, and I would be very sad if GTAV was first-person.

It may not put you in the game, but it is more immersive. Watching stuff happen to a character is not the same as seeing it from his eyes. When a car is about to hit you, in 1stPV you may flinch while you would not in 3rdPV. I think the problem is that most games that use first-person view are lazy... the player has very few animations, you can't see feet and hands, etc. Third-person views can't get away with that. That's why 1stPV in GTA is ideal, you have all the work it took to animate a character but then you bind the camera to the character's head. You see your arms push open a door, you look around before yanking someone out of a car, and your view tumbles around when you jump out of a car. When you drive a bus, you walk inside and sit down at the wheel, you aren't driving it from up in the air 10ft behind. Most of my problems with GTA are from fighting with the camera, not a problem in 1stPV.
Ultimately it probably depends on the game. A game focused on a character and his/her actions is better for 3rdPV, while a game focused on the surrounding world should be 1stPV.

Crump, if you were in an actual high speed car chase and you were driving by some funny billboards you would not take the time to notice them.