Sturmey Archer AW has been in production for 8 decades. I own three of them, each around 50 years old, and I've never seen one that was not either 100% functional, or trivially repairable. Huge numbers were made. The current production AW models are very close to the historical design. Spare parts are readily available, and are interchangeable across the decades. Its gear range is sufficient for a pretty wide range of riding conditions, yet it's simple enough for a layperson to service.

So it's also in a class of its own.