FWIW, I have had a JD X360 for quite some time and do all maintenance including valve adjustments. Not difficult stuff and I can easily get parts. That is really important to me. Having said that, I would probably have gotten an X500 series based on what I have come to use this lawn tractor for over the years. If you are just cutting grass and maybe pulling a heavy cart on flat ground, no problem for an X360. I have a leaf and lawn vac from DR. From a dead stop on steeper hills there is barely enough power to move up hill. I would imagine a fully loaded cart might present the same issue. Yet, with this kind of use it has held up nicely on 3/4 of an acre. There are other times I get wheel spin, so 4 wheel drive on an X500 might be a consideration next time around. It's all about your specific situation. Budget, use and terrain.
As for Made in USA, I'll buy US made whenever I can. I have purchased well-made US products and I have purchased poorly-made US products. I'd stick with what gets decent reviews and a dealer that backs their product. My local JD dealership has given me no reason to switch to another brand.