Just got back from Nepal a couple of days ago, where my partner and I were doing an Everest Base Camp Trek assisted by Nepal Hiking Team. Their service couldn't have been better. I started planning this trip last Spring and looked at numerous trekking companies.
Chose NHT due to the tremendously positive reviews on them, the professionalism of their website, and the quick response I got from Ganga when I sent an initial inquiry via their website, he phoned me within a few hours, apparently as soon as the morning had come round to Nepal (given the time difference between North America and Nepal).
He was extremely helpful and responsive from the start, all the way through the completion of our trek and the last couple of days back in Kathmandu. Our guide for the trek, Bhim, couldn't have been more helpful and took very good care of us and kept us safe. The whole operation and experience couldn't have been more positive.