I have just completed a trek to Upper Mustang with Himalaya Guide Nepal Pvt. Ltd. and it was a very positive experience. The reason I chose this company from several others was due to the quick and professional responses from Chandra, the head of the company, and their reasonable pricing.
The organization of the trip was impressive, starting with a seamless airport pickup. On the trek, my guide Dinesh, who is local to Upper Mustang, provided an insightful experience. His knowledge of the local dialect, culture, and lesser-known trails enriched the journey significantly. He was pleasant and professional, making the trek enjoyable. He also gave me invaluable advise on food, so I have never had any problems with stomach (which I afraid at the beginning of my trip).
My porter, Binod, also added greatly to the experience. His handling of the luggage was efficient, and his positive demeanor, including occasional humming of folk songs, brought a unique charm to the trip.
This trek was memorable, and I am considering returning to Nepal for the Annapurna Circuit.