Sixties Cher is the only Cher as far as I'm concerned. I'm not too keen on what she recorded in the seventies, and absolutely detest what she's recorded since the eighties (I have a similar opinion about Tina Turner's output, gimme Ike and Tina over solo Tina any day).
My favourite solo Cher tracks are "All I Really Want To Do" (1965) and "Bang Bang" (1966).
My favourite Sonny and Cher tracks are "I Got You Babe" and the brilliant "Baby Dont Go", both from 1965.