Richard Vandersteen - He gave me phone time to discuss speakers (his 4As) that I'd bought on the used market, and that he no longer sold in that form. I mean, serious phone time. This was the late '80s. I couldn't believe how well he treated me. He actually took the time to educate me about psychoacoustics & the benefits of 1st order crossovers!
MHDT Audio - Jiun-Hsien, who patiently answered every question. I ended up buying (and loving) MHDT Labs' Orchid DAC. No regrets there.
Lake People/Violectric - Fried Reim. He's the boss & chief design engineer. Fried makes terrific products (I own 2 of their amps) and has treated me very well in person and on the headphone boards. I'll buy their products again for sure based on solid engineering & terrific sound
Power Holdings (LP/Violectric's US distributor) - Arthur (sorry, no last name) has treated me very well in person and via email. A class act.