I've been doing the same comparisons of KOREAN tractors, as well. I'll share what I've learned:
Kioti (Daedong) manufactures their own tractors with their own engines and controls their own distribution - the same business model Kubota uses.
I'm not sure who actually builds the Korean tractors for Long (I saw it on another post, but can't find it), but they use both Kioti/Daedong and Mitsubishi engines for the Landtrac (Korean series) and are built for Long Agribusiness who distributes them.
Kukje builds tractors for both Century (AMJAWA) and Branson using Kukje and Yanmar engines with distribution handled by their respective importers.
Tong Yang (TYM) builds Mahindra using Kioti/Daedong engines and Scorpion (formerly Millennium) using Kubota and John Deere engines (hecho en Mexico??). My understanding is that Tong Yang handles Scorpion/TYM distribution in the west directly and Decker & Co. handles distribution in the east.
I have driven everything on this list, except the Tong Yang products and they appear to be world-class quality close to, equivalent to, and even exceeding what I have seen in the big three. I expect the TYM's to be up there too. My feelings are as follows:
The Longs have the most standard equipment.
The Kiotis have the most standard equipment for the price.
The Kukjes are the most affordable.
The TYM's seem to fit in with the Kukjes and Kiotis.
IMHO, these are all worthy pieces of hardware, but that is just one piece of the puzzle. I think the deciding factor will ultimately be the dealer. One brand I am seriously considering has a dealer that is selling out of hand-made buildings in the middle of a farm field. Another dealer for a lesser known brand operates in a converted auto showroom with a four bay repair shop. The guy in the pasture has a slightly better price, but the guy with the service bay has a hoist to crack open the tractor if necessary. Who is going to get my business? I still don't know.... But, I feel that organizational support BEHIND the product helps you find the VALUE you get for your money. I'm hoping this thread will help me make some decisions, too.
JMHO, but I want to share AND learn.
Mark