Recommended hotels in Sultanahmet & Taksim (Istanbul)

Happy Thursday everybody!

Can anyone recommend any particular hotels in the Sultanahmet or Taksim areas? Obviously both areas have a large number of hotels at different price points and I'm keen to find a few that stand out. I've been asked by a client for recommendations for a non-business related trip - value-for-money, cost and service is important to him.

[n.b. if you are affiliated with a hotel or work for a company that promotes hotels or is in the tourism business please state so]

Many thanks in advance for your answers.

Stu