grammar - "It is he" versus "it is him"

Which of these sentences is correct?

It is he I relate to most of all.

Or,

It is him I relate to most of all.

I believe that in neither of the two sentences do the words "him" or "he" act as a relative pronoun, for the simple reason that they are not relative pronouns. Instead, both sentences have an implicit relative pronoun. The case of he/him should depend on other considerations, such as, the proper case after the linking verb, "is".

It should be simply a matter of which is more correct,

It is he

Or,

It is him

My Latin education would have me pick the former. But my knowledge of colloquial English tells me that the phrase, "it was him", is commonly used. Thus, I do not know. I hope these words help explain my reasoning, without making my reader more confused. I would be interested to know what you grammar gurus think of my first two sentences. Which is correct?

Answer

'It is he' sounds very formal.

'It is him' is grammatically correct and is in common usage.

HE is used for subjects and predicate nominatives.

HIM is used for objects of preposition, direct objects and indirect objects.

You could rephrase the sentence: I relate to him most of all.