Harley Davidson makes the best machine out there. The heavy weight of the Harley bikes is a real advantage on cross-country trips, and the bikes last forever if you treat them right. They're easy to maintain and repair. Plus, no other brand has the sheer cool factor of the Harley Davidson brand.
Harley Davidson is a brand that has been around for over 100 years and has still remained relevant. They are able to morph to trends and new technology and continue to make motorcycles that are driven and coveted by many around the world. Clearly, they make a great product that are the best motorcycles in the world.
Harley Davidson has always taken pride in building its motorcycles, and refused to compromise this quality even when they went through financial difficulties and almost bankruptcy. They have continued with this type of quality build, and I think that means they still make the best motorcycles in the world, with the best service records.
Harley is basically building to a brand by now. They make decent bikes, but are generally riding on their brand name and image. There are other bikes built for more speed, better safety, and better looks, though the Harley Davidson image is still strongly desired. Like with other vehicles, there likely isn't an objective "best" brand.