Have you sat on all three tractors yet? Each one has a different feel, one of them may just feel like it fits you better. If you're thinking of getting the MX5100 in HST the forward/ reverse pedal is a little different than the others. some like it a lot, some don't. Try the loader out. Does the lever feel like it's where you would want it? Finally talk to some of the people that work at the dealership. Do they seam friendly and willing to offer advise? Do you feel like they are there to help you down the road? Maybe ask them some of the questions you ask us as a way to feel them out. A good dealer is a valuable asset.