Um - just about anything, I think; except, strangely enough compared with so many answers, I think the hand is my least fave.
Maybe I just need more practice...
Hand is definitely not my favourite either...
For me, it's a cane. And not just my favourite spanking implement, but just about my favourite kind of pain there is. A nice caning gets me giggly & happy, and the marks are just marvellous.