Barleywine
Either I didn't know any better or I'm just a masochist, but I started with the Thoth back in 1972 and stayed with it until I joined here in 2011 and began buying more decks. It's like one of those old-fashioned "shoe-stretchers" for your brain. I recently bought the Robin Wood and find it a fine example of the RWS style with a pagan overlay. It makes an excellent first deck.