"Venus," definitely Shocking Blue over Bananarama
"Pinball Wizard," Elton John over the Who
"Lucy in the Sky," Elton John over the Beatles
"Spooky," ARS over Classics IV
"Stand By Me," John Lennon over anyone else
"The Power of Love," Laura Branigan over Celine Dion, even though I got to hear Celine sing it live a couple of years ago; I will obviously never get the chance to hear Branigan sing it live.
"Roll Over Beethoven," ELO over other cover versions
"Hushabye" Beach Boys over Mystics
One country cover that I actually liked was Johnny Duncan's cover of "Come a Little Bit Closer." His use of a female vocal (Janie Fricke) on the chorus was sheer genius! And he still managed to keep that "south of the border" flavor to it.