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.
it depends on how you manage it, sometimes we value bitcoin because we can have a profit on it , we can have an extra money for our everyday needs, and it can help us to buy and provide the things of our families it can also help us to have an investment for the future, bitcoin really help us so we value it as a source of income for us.