You might research the endless-sphere forum for a good answer for that question. The type of motor your asking about (internal gear reduction hub motor) is the type I have the least experience with. I can tell you that I have had good luck with a Crystalite direct drive big brute hub motor and have many thousands of miles on it but you weren't asking about direct drive hub motors.

I can also tell you that I personally have had very bad luck with brush-less motors that have the controller built into the motor. A very bad design in opinion frustrating maintenance, adding weight to a wheel where it is least needed or wanted, and considerably reducing reliability. Give me an external controller any day, I'll always pick it over a built in controller. I've already had to bypass a couple of them and re-wire to use an external controller.

As to china made = trash. Yes, that can certainly be the case but not always, if you pick and choose carefully you can end up with a decent system.

Personally I really wish a good company out of one of the East-European former iron curtain nations would start making a good line of e-bike components for internet/mail order to the U.S. I have several machine tools and other high quality merchandise I purchased internet/mail order from such sources and they are some of the best quality I've ever had the opportunity to own at very reasonable prices with KISS type engineering that is simple solid and reliable. I dare say that most of the quality merchandise I have purchased from those kind of sources puts "Made in U.S.A." stuff to shame.

Customer service experience has also been great to incredible. Seems to me that people who know what oppression is and have at least in part overcome it and are eager to make their own way seem to make the very best stuff and know how to make good solid simple quality at a reasonable price without a bunch of unnecessary frills and whistles. Something that we seem to have forgotten even when we still manage to get around to make some stuff ourselves.