Unfortunately, the current U.S. situation makes things a bit sticky because
1) The Federal and State governments are already heavily involved in licensing and sanctioning marriage.
2) A Federal law passing “Marriage equality” would allow homosexual couples to marry in any state. Those with same sex attractions would probably argue that this makes them more free. However, it would also bring about other mandates for public education [with regard to sex ed, family life, etc.]. Also, it might bring about coercion of businesses with regard to other matters [e.g. a photographer was forced to take wedding pictures of a same sex couple].
3) What is truly the best policy for the U.S. regarding this issue? I honestly don’t believe a Federal Amendment would be a good way to proceed. Perhaps, it should just be left to the states? That then invokes the problem of whether the people of the state will get to vote or if judges of that state will just decide for the state.
4) It certainly seems like the mess comes from having the State so entangled with marriage in the first place.