What is the most important topic to argue when in favor of legalizing

[bafisch89]

same-sex marriage? I'm writing an paper for my English class right now and the topic is whether we are for or against same-sex marriages. Obviously from my question, I am in favor of it, but I could really use some help in what's the most important to consider when defending my argument and defending it effectively. Some things I've heard in defense range from civil rights to the varying federal and state benefits that a couple can receive upon marrying as opposed to having a civil union. I would just like to have some opinions as to what you think is the most important to consider.

ps. if you have some online references and resources, that would help tremendously as well!

thanks!