I think that the most common way to value Bitcoin is like valuing other currency by another currency.
Seeing to it that we all know all the factors that causes or affects supply and demand equilibrium.
Also the time we hold bitcoins. Time is very important factor.
I value bitcoin so much because bitcoin has already helped me a lot especially in my finances. With bitcoin I am able to gain so much money with just using the less of my time and the less of my effort. With bitcoin I am able to help my parents in the financial need that I need and I am also able to buy things that I want.