If you’re a conscientious writer who strives to be grammatically correct 100 percent of the time, but you still struggle with choosing between who and whom, take my advice: Choose who. If you’re wrong, 90 percent of your readers won’t know it and the rest won’t care. If you choose whom, you might be correct, but your writing will sound pretentious and stilted. And if you’re wrong, you might be mistaken for a writer for Yahoo! Shine:
Could that sound any uglier? The correct word happens to be who, because the pronoun is the subject of the verb had. The pronoun who is the subjective case (and hence, the subject of verbs); whom is the objective case (and the object of verbs or prepositions).