Which of this year’s nominated roles couldn’t have been done as well by any other actor?

This idea came up indirectly in another post but I’ve been mulling it over for a while. Of the 20 nominating acting performances: which role(s) do you think were the perfect marriage of part and actor?

That’s the more interesting question, I think, but then also, which roles do you feel like other actors, specific if possible, could have been played just as well or even better by someone else?