Which of Brad Pitt's newest looks is best?
In colloquial speech, we often omit words for economy of speech, when it doesn't alter the meaning of the sentence.
The full sentence would be:
Which one of Brad Pitt's newest looks is best?
The subject of the sentence is 'one', and takes the singular verb 'is'.
So, "Have you been following Brad Pitt's latest hairstyles? Which one is best, do you think?/Which one do you think is the best?"
'of Brad Pitt's newest looks' is a prepositional phrase.
"Looks is deceiving" is a purposeful grammatical error - a kind of child-like 'mistake' because the person is uttering (I think) a proverb that borders on being a cliché. Whilst the speaker really means it - Looks can be deceiving/Don't judge a book by its cover - he also mocks the fact that he is coming out with/is actually using a cliché** by purposefully making a child-like mistake in grammar.
** to use clichés in one's speech is to seem prosaic (=commonplace), to lack style
David, you are superb!
I was also thinking about 'which one of Pitt's looks...', but as I am not a native speaker I am not so sure. It's a pity I can't find any explanations in any of my grammar books - Michael Swan's 'Practical English Usage' or Raymond Murphy's 'English Grammar in Use' or others.
I especially like the fact you are a British teacher, so kind and prompt. Thanks a lot!