Stalnakers, the local LS dealer, only stayed in business for about 5 years and went under.
I think if you check around this site, you'll find there are three situations for tractor owners. First, they bought a flawless machine (most common). Second, they bought a machine with some issues and had a good dealer experience. Third, they bought a machine with some issues and had a bad dealer experience. You'll find these three situations occur within all brand labels.
I also understand your concerns about who makes what. The thing to remember is that "re-engineering the wheel" is how companies like JD end up with proprietary parts. There is something to be said for the manufacturers that source good products from good suppliers and implement them into their machines. Having a good quality part used across many brands and models just means that part is easier to find and cheaper to source if you ever need it. Chances are, you'll never need to. You wouldn't have many manufacturers sourcing the same parts if the parts were prone to failure or something else could be made better or cheaper.
I think in talking to tractor owners, you'll learn the most important thing about being pleased with your tractor purchase is to ensure you go to a reputable dealer. Good intentions on the dealer's part aren't good enough. You need someone that has a proven track record with the company they represent. Most times, any warranty work you need completed will be approved or denied based on the dealer's ability to convey the situation to the corporation and what sort of working relationship they have with the corporation. There have been cases of legitimate warranty claims being denied because dealers have misrepresented past warranty claims and the corporation doesn't trust what the dealer is telling them, or there is additional wait while the corporation sends a technician to the dealer to confirm what the dealer is telling them. Good dealers that can find the proper balance between taking care of customers and protecting the corporation from bad warranty claims are difficult to find.
Finding a good dealer should be the top priority. All brands have good tractors and bad tractors.