Which is better screen gorilla glass or amoled?

The amoled is a better screen because it (active-matrix organic light-emitting diode) is a display technology. While Gorilla glass is a damage and scratch resistance sheet of glass used in many modern phones as a cover overtop of the screen technology but as of yet isn't a display technology on its own.

These days most phones use both of these in combination. Samsung Galaxy S2 uses a "Super AMOLED Plus" display and a Gorilla Glass plate overtop.

So you can't really compare the two.