Well I can help you. I have operated a 903 on my farm for 2 hay seasons. We put up 700 to 800 large round bails a year. I mainly used the 903 to operate the bailer.
I no longer have the 903 and this year am using a 1003. If you are trying to decide between the two of them, hands down, go with the 1003. On paper they spec out the same except for hp and pto. However, maybe its just me, but the ease of operation, smoothness of the engine, transmission, etc, is much better in my experince with the 1003. The bailer I run does not really require that much hp, so I don't really see a big difference there, except the gearing seems to work a little better with the 1003. I can run between high and low range in a gear instead of often having to re-gear.
I have to say, my experince with TYM has been very good. I think they are a fine company and would recommend their product to anyone. I got to them bc I have owned a Mahindra 6000 for years now and it is still the overall work horse on my farm. It is built like a tank and has done everything I have asked of it and more. As you may know, TYM made many of the Mahindra tractors for some time. I see a lot of similarities in the two. The Perkins engine in the TYM is superb, traction, etc is very good. The cab on the 1003 has been a joy so far, air works great, radio, etc, all good. The hydralics on the 1003 seem much smoother and easier to operate than on the 903. Again, it may of just been the 903 I had.
The others you have named are also good machines. I would like to say that dealer support these days is not as important as it once was. Many companies have gone to a transit type dealer set up. You will find these type brands are picked up by dealers of lawn equipement, grills, and all sorts of items. They really rely upon corporate hq and warehouses for parts, direct ship to customers, and they hope with todays quality controls that there product will operate without major problems so dealers are not as important. However, that works fine as long as you dont have a major issue with the tractor. As I have read other posts of TYM problems and other brands, getting someone these days that really knows how to work on tractors, break them apart, etc., is much more difficult to find these days.
My take on it is you really need to find someone in your areas who knows tractors. If they are truly a mechanic, they can work on any of these machines with a little assistance from the manufacture. Of course, the other way to go is pay the extra money and go with an establishe name brand that probably has a full service parts department and service department, but be prepared to hang on to your wallet.
Hope this helps.