The Old Galactics in James H. Schmitz's "A Tale of Two Clocks" (a.k.a. "Legend") were a spacefaring race, but they probably wouldn't want to contact us.
think I would go with some of the bad sci-fi aliens from bad old sci-fi movies or spoofs...hot females that have no standards and that just need men for breeding.
The Culture. Though we'd probably never know they were here until one of them went on a drunken bender and had to be forcibly beamed up by his friends.