Neither Bill Nor Hillary Supported Marriage Equality in the 1990's.

[Agschmid]

50. All our candidates evolved on this issue.

Vermont Sen. Bernie Sanders likes to describe himself as a longtime supporter of marriage equality—in sharp contrast to his Democratic rival Hillary Clinton, who’s still striving to convince her base that she’s on board with LGBT rights. In May, Sanders famously told New York Times columnist Gail Collins that “I’m not evolving when it comes to gay rights. I was there!” Liberal outlets consistently describe Sanders as a pioneer for marriage equality. As proof of his pro-LGBT credentials, Sanders frequently touts his opposition in 1996 to the Defense of Marriage Act, which barred the federal government from recognizing same-sex marriages.
Mark Joseph Stern Mark Joseph Stern

But Sanders is not quite the gay rights visionary his defenders would like us to believe. Sanders did oppose DOMA—but purely on states’ rights grounds. And as recently as 2006, Sanders opposed marriage equality for his adopted home state of Vermont. The senator may have evolved earlier than his primary opponents. But the fact remains that, in the critical early days of the modern marriage equality movement, Sanders was neutral at best and hostile at worst.

Source.

Yes he is better than Hillary here, I agree. But the record isn't blemish free.