Of the ones mentioned so far, I like these versions of Jealous Guy and Hazy Shade of Winter in particular.
Another good one is Dave Stewart and Colin Blunstone's version of What Becomes of the Broken-Hearted?, as it is distinctive and almost as good as Jimmy Ruffin's version.
Bananarama's versions of Really Saying Something and Na Na Hey Hey Kiss Him Goodbye were enjoyable, but their version of Venus not so good.
plenty of my favourites already mentioned (Tainted Love, The Day Before You Came, Always On My Mind, It Must Be Love, Jealous Guy) but my most cherished has to be Grace Jones' version of 'Private Life' in 1980