I use 'bumper' cam in GT Sport.
The most important thing to me, is to have my 'eyes' in the right place.
My viewpoint must be as close as possible to actual height above ground as it would be in real life,
and it must be placed so that i can know where the front wheels are.
In most games, cockpit view can usually provide this viewpoint, but unless one is running triple screens or VR,
cockpit view is horribly unrealistic because of the unnaturally obscured vision.
If you can't 'look around' when you're in cockpit view, it's not giving a reasonable representation of a real driver's view.
I'm always amused at the folks driving cockpit view with one monitor, describing it as 'realistic' & 'immersive',
and I wonder if they've ever actually driven a car in real life.
Cockpit view on one monitor fixes your view straight ahead, and there is a virtual black curtain covering 90% of the driver's side window,
and the black curtain is also covering the passenger side window, and 25% of the front windscreen.
No driver in the real world would tolerate that kind of extreme intrusion on their vision.
In an actual driver's seat, your head moves front to back, and side to side constantly,
your eyes fly around, and your brain paints a mosaic, a 'latent image' of the whole scene.
There is no A-pillar, no windshield wipers, ... your brain is just seeing the unfolding shape of the road, and locating your front tires.
On my PC, I play DiRT Rally, Assetto Corsa, and others on triple screens ... in cockpit view.
Right now, I'm missing racing my buddies online in GT6 on triples, with my 3 PS3's ... in cockpit view.
But cockpit view on a single screen doesn't cut the mustard with me.
(I make an exception in the case of open cockpit cars, they're not as bad on one screen)
Bonnet cam works well in Assetto Corsa, which is good, because their bumper cam feels too low to the ground & too forward.
DiRT Rally bonnet cam is also a good viewpoint.
And this gets rid of the A-pillar & clutter, that your brain ignores in real life, so that's good.
Another cool thing a good usable bonnet cam gives you, is a nice little visual of the front of the car,
a long or stubbie bonnet, some color, and more sense of relative movement to ground.
'Bumper' cam in GTS put my eyes at a realistic height over the tarmac, and right behind the front axle,
with nothing unnaturally blocking my vision.
All the other cams, besides cockpit, are too far away from where the driver is, so I can't enjoy them.
Sometimes I drive GTS in cockpit view! Because I can, and because they have all those blinking lights,
and cool knobs, and switches, and stuff.
I do prefer that a game offer the option to exclude the wheel & hands in cockpit cam.