I had always held up Beyonce's "Crazy in Love" as the benchmark for the modern R&B/dance single. It's the best one and, honestly, nothing has come close since (Alicia Keys' "No One" may be the closest, but even that's not very close).
Why do I bring this up? Well, Beyonce may have done it. She may have bested herself. I'm not positive yet, but it's damn close. "Single Ladies" may be the best R&B/dance single of the modern era (which I put at, well, the last fifteen years). While the subject matter may be a bit anti-feminist (why should a woman need to be engaged to feel fulfilled in a relationship? Not all women even want to get married), it's infectious groove, killer chorus and "woah,oh, oh's" (also used to brilliant effect in "Crazy in Love")put it in the pantheon.
Congrats Beyonce. You're officially our generation's Tina Turner and that's no easy feat.
PS: While I don't own any Beyonce albums (I imagine there's a lot of filler) there is no way that her greatest hits record is not going to be a five star perfect, all-time top album, like Immaculate Collection good. Think about it, "Crazy in Love", "Ring the Alarm", "Deja Vu","Baby Boy", "If I Were a Boy" "Irreplaceable" and "Single Ladies." Shit!