Collar height is a matter of taste subject to a few guidelines. The advice that you should only show 1/4 inch of collar in back above your jacket collar to match the 1/4 inch of cuff showing at the sleeve is too strict a rule since it doesn't account for neck height.
Most people here are probably up to 0.5 inches in the back. I think it looks quite nice when done in proportion to the person's build.
One of the old Put this On videos has Flusser demonstrating why collar height matters on long necks...was a revelation to me:
Just rewatched it... about 5:31 min in.
BTW: I disagree with Flusser's advice on lapel width for the thin guy (Flusser suggests thin lapels for thin people; I'd go wider lapels).
If the collar is too low in the front it looks "wimpy" and just sad. A nice high collar is a beautiful thing (Betelgeuse from Mexico in the WAYWRN thread photographs his collars nicely to show why it is a beautiful thing). You can see the difference when Flusser pulls the guy's collar up.
Not too high so that you look like you are in a straight jacket!