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.
Bitcoin is so very important to me, I value my bitcoin like a treasure. I always saved all the bitcoins that I earned from many campaigns. I know that the bitcoin will give me a wonderful life in the future.