Cher may not be the original, but when Mermaids hit theaters - my mom was in love with Cher, and I was in kindergarten and easily impressionable - so her version still wins for me.
I'm pretty sure "If I Could Turn Back Time" started my love for Cher. I remember seeing the video as a kid - and something about all of those sailors really did something for me. But it was when I first saw her video for "The Shoop Shoop Song" featuring a tiny Christina Ricci and my first Gothic love (thanks to Beetlejuice) Winona Ryder, that my life long worship truly began.
In college I finally had my chance to see Cher perform the song live. I think that also contributes to her victory in my sing-off judgement, but there are so many awesome covers - mostly from the 1960s - that it is difficult to decide.
As usual, check out the clips after the jump and let me know who you think did it best. If there is someone I left out, post a link in the comments.