What's the most reliable brand of dirt bike? And easiest to fix.?

They are all about the same (speaking of the big 5). KTM's do not cost that much more where parts are concerned and when it does it's only because you are getting a better product. KTM does use better brake pads, chains, sprockets, etc. than the Japanese bikes so sure it will cost a little more, but you get what you pay for. If you are looking at a 250 2 stroke I would go with the YZ250. It's power delivery is better for a wide variety of riding styles. No it is not true that one brand is more reliable than the next.