I can think of several who didn't receive the Nobel Prize who would have been worthy winners. Italo Calvino, Vladimir Nabokov, Marcel Proust, Mark Twain, Checkov, W.G. Sebald and Jorge Louis Borges amongst others.
Yes, certainly Mark Twain.
Naipaul is a man who can write but can't talk. His writing is brilliant --- if some say he is one of the best writers of English prose today they may not be wide of the mark --- but his tongue is too sharp and his views too outrageous for the comfort of too many people. I once became the victim of his sharp tongue. In the part of the world where Jayaprakash lives, I met Naipaul. A friend of the author --- yes, he has, or at least he had, friends --- had another friend who was my boss at the time. I was asked to suggest to Naipaul names of some people who could get him certain information for a book he was writing. I did. And what do you think Naipaul did after I reeled off some names? He smiled graciously and thanked me profusely? No, sir. He blew his top and shouted at me for suggesting to him wrong kind of people, in full view of at least a dozen people who were in the restaurant where we met. He went into a loud monologue on what sort of people he wanted to see and asked me to come back in a couple of hours. I never did.
I do wonder sometimes whether he could be forgiven for the kind of things he says because of the sheer brilliance of his writing.