Ann and Nancy Wilson.
Best YouTube Comments:
“I leaving my teens when this song hit the airwaves. And that was the era when Western music (or any music for that matter) was at it's peak, and I was in my beloved Penang. Some combination. Music has degenarated to the shit we are listening to today. But we have the music of yesteryears to sustain us.”
(Me: Not everything today is shit. And there was bad music back in the 70’s and 80’s. This song however is a classic.)
“She's so beautiful, and her voice is so fucking awesome.”
“When this song comes on the radio I roll the windows down and crank it up. Love this song!!!”
“That singer is sexy AF.”
“If I didn't watch the video, I'd not have believed it was from 1977! It sounds quite modern.”
"Hayley Williams mom?"
(Sorry, couldn't help adding that last one. 
Except that I think Ann is the age of my mom. I was born "before 1985" and Hayley was born "after 1985" 
We could go in endless circles debating who is better. But yeah, I basically agree with the Ann/Hayley comparisons. They're both beautiful and talented with amazing voices. Would love to hear Hayley do "Crazy on You." 
)