Two of the most important things that went into a great lead singer in the 90's: Heartbreaking lyrics and apparent disinterest in singing them. Hope Sandoval is my favorite example. Found this VH1 performance while searching for "Guitar Players With Sideburns Wearing Berets". Mazzy Star was Lana Del Rey for drug users.
Editor's note: At first I thought, it's crazy I've never seen this, then i noticed it aired on vh1 europe. I think the world was bigger back then.