Of the 3 tractor the OP mentioned, the Kioti is the best choice. The JD and the NH are the basic economy models, while the Kioti is the deluxe tractor of that series. If you have a good quote on a DK, get it, because the series is no longer in production and are becoming very hard to find now new. The DK is also thought of very highly around here. If you want the comparable JD, look at the R series, although they are quite a bit more expensive. Also the Kubota Grand L series does not have the treadle, and very nice tractors, although you are looking at about 30K baseline. LS is good too, although they are quite a bit lighter for their horsepower than I think they should be, this can be good or bad depending on use. I could name every maker out there, but you have to set limits somewhere. In my opinion, when I looked a few months ago, the Kioti DK was the best value tractor in terms of horsepower and features for the price. I ended up with a CK for size reasons, but in your case, especially with JD dealers attitude, I would go with the DK and not look back.
Some bias here, but not much. If not Kioti, definitely look at LS, and the Kubota Grand L3560 if it's in your budget.