good but difficult question
That's such a tough question. For me it changes almost daily as I discover new aspects of poets that I had previously not known. Also mood affects me greatly - somedays it could be Robert Frost, somedays Oscar Wilde, some days Robert Louis Stevenson. When I came across Philip Larkin's 'this be the verse' I didn't get over it for days. I guess if you really pushed me I'd probably have to say Shakespeare, he really is extraordinary. But I reserve the right to sway with the wind.