What's her best?

Besides portraying Catwoman? Probably singing Santa Baby.

I agree with the previous reply that her Catwoman character and the 'Santa Baby' record is essential. Her records generally don't compare to seeing her perform live. I've only see her singing live on TV shows and that can be a scary experience. She sings a love song with menace. It's only when she gives a cackle at the end that you know it's been done strictly in fun.

I see repeats of performances she did on 'Jools Holland's Happening' (1991) and 'The Good Old Days' (1976 and 1973). I can't remember offhand the songs she sang on those broadcasts. But they should be worth a search on You Tube in case somebody has put them on there. So look for her singing live in intimate studio surroundings I reckon to see her at her best.