The only manufacturer names I've seen batted around are Joye, DSE, SLB, and Bauway. There are a lot of different attys (high or low voltage), but these may or may not be custom runs commissioned from one of these main factories.
The way manufacturing works in China, they could all be coming out of the same factory, or out of a dozen. Companies pop up, go away, change hands and change names all within weeks. Unless you're in the industry in China, I don't think it's
possible to know who is making what for whom. Honestly, it's probably best to not even worry about it. Find a
shop who sells a product you like, and stick with them. At the end of the day, does it really matter whose company name is on the import slip?