What is preferred for glaucoma testing--puff-air or applanation tonometry?

Usually applanation: Air puff was developed for optometrists when they wisely were not permitted to use eyedrops. Because their skill level is less, they still prefer to use the air puff as it is less tricky. But the airpuff is not as accurate - it is a good screening device. Applanation is the gold standard, more accurate and precise but requires much more skill to use. So it is a tool of the ophthalmologist.

Applanation: Goldmann applanation tonometry is the gold standard for measuring eye pressure. "puff" tonometry is inherently less accurate, and mostly used only as as a screening technique!