what the city in HK that is nearest to some tourist spot & most accessible to any other place in HK

Actually, the transportation in HK is quite convenient. Public buses and subways are good ways for tourist. And almost every station has clear English sign.
So it's not necessary for you to find the most prosperous area in HK. If you still wanna to stay, you can stay on HK Island, like Central, North Point, Admiralty, Causeway Bay or Tsim Sha Tsui area. :-)