My preference is the Automation Direct GS2 ($251) and GS3 ($293) drives, and 2 day free shipping. They have served me well for many years in addition to excellent documentation and customer service. I use 3 of them in my shop, and have installed several for customers.
I have only had my hands on a couple of the Huanyang units, and found then to be a bit of a pain to program due to the poor documentation and translation. Nothing wrong with the YJ200, but I have a 2 year old one out in the shop that blew up. That is not to say that they are all bad, just that particular one blew, and that's the only one that I have heard of that fried, and I don't really know it's history. I replaced it with a GS2 and as far as I know it's still running.
Never used an Emmerson.