The right collar for the shape of your face:

If your face is round you may want to wear shirts with a Point Collar. This will make a round face look slimmer.

If your face is more oval or angular you may want to wear shirts with Spread Collars to complement your face shape.

It is important to keep in mind that when wearing a tie your knot should "fill" the spread of the collar appropriately.  Meaning, for Point Collars a Four-In-Hand is appropriate and for Spread Collars a Full-Windsor is appropriate.