I've been using the center point focusing on the 5d MkIII almost exclusively since I got it. For static objects or portraits, I'll use the single focus, then recompose. With moving objects I've been using the AI servo mode. My reasoning for this is that I'm nervous that the autofocus won't focus where I want it to.
I'm not sure if this is really the best method or not, it seems to me I should do this wotb portraits, focus on the closest eye then recompose. However, I do a lot of airplane wildlife photography, would I better off using the focus system differerently?
I guess I just need some advice on when to use the different autofocus settings.
The benefit of having multiple focus points is that you can choose the one you want, instead of focusing and recomposing. This provides more accurate focusing because you don't have to move the camera. You can use the little joystick to select the point you want. You should never use auto point selection, because the camera will just focus on the closest object, which may not be what you want.
61 point AF is the main improvement between the 5D II and the 5DIII. If you don't use it, you might as well just downgrade to a 5DII and save $1500.