My girlfriend and I did the Langtang valley and Gosaikunda Lake treks with Himalayan Local Guide. The company was professional from the start and much more affordable than other options.
They had quick and friendly email responses (even on US time, when it was late at night in Nepal). Our guide Bashanta was friendly, knowledgeable, and professional. At each village/hotel he made sure to show us any cool features and went out of his way to make sure we got good rooms. Next time we do a trek in Nepal we will use this company again without a doubt!
