Whiterun/Solitude, Whiterun for its central position and nice look, (I would love to see Falkreath, it's one of the two cities I haven't yet been to, (Falkreath and Dawnstar) and I'm 60 hours in the game, feels like I still got a massive load to do :biggrin: ) and Solitude for its awesome house and big-ass city look, to me it feels like the only real "city" I've yet seen, it's big and the first time I visited it... I got lost within seconds... (Though I tend to get lost in the Gray Quarter or Windhelm too :rolleyes: )
I know exactly what you mean, I've yet to visit most of the other hold's let alone town's and cities, only yesterday did I discover the temple to Kinnerith in Whiterun, all the time I have spent there and only yesterday I discovered the temple.