The choice you make has to be personal since this is a vital decision of your life. If you feel that you need to be genetically related to the child, then you need to choose surrogacy procedures. Today, we have traditional surrogacy as well as gestational surrogacy. In traditional surrogacy the mother uses her own egg and the sperm is introduced via artificial insemination. And Genetic surrogacy is, where, the surrogate carrier carries the eggs/sperms of the commissioned couple.
The other reason why many couples prefer surrogacy is because they get to choose the surrogate mother. They are fully aware about the background of the mother. When you adopt a child, you do not know the background of the parents.
There are many anti-gay adoption laws in many states and countries and this does not rule out the self proclaimed enlightened countries. There are lots of people who are strongly against gay and lesbian adoption. Since it becomes very difficult for gay couples to adopt children, and surrogacy is the only option left for them to have a child.
In India Surrogacy can be opted by Couples, gay, same sex couples.