I would like the Pillow (as long as it could turn into non-fictional characters as well and they do whatever you tell them to do),
the Dressing Gown,
the Reincarnation pill (as long as I can siphon it out of my faeces and re-use it) and
the One Ring (as long as I can use it's full potential without any 'bad things happening'
(I can't remember the word that means 'bad things happening in the future' that starts with 're'.))
But as I would be foolish to complain about having just one of these,
I choose the One Ring, as no one knows who you are when you wear the attention-drawing Iron Man Suit and the Pillow and Reincarnation Pill don't live up to their potential (as specified earlier.)