I remember stopping by a local bus service shop about 10 years ago. We were looking to find a place to service our coach, and so were interested to see what this shop had to offer.
When I walked in, there were several fellas sitting around, chatting, and when I explained our mission, they explained that the shop serviced buses with Detroit engines. They then asked what kind of engine our coach had: 'Cummins', I replied. "Oh, good engine", they responded ...
I've had several such encounters over the years and have found that owners of Cat, Cummins, or Detroit engines are all happy, regardless of the paricular manufacturer. Why? I think it is because all the engines are very well built, heavy duty pieces of machinery. What matters more is whether the particular engine in a coach meets the needs and expectations of its owner. Some people want to be able to drive over the summit on I-70 going West from Denver at 70 mph; others are happy just to get over the top!