Aww c'mon Alex, it's bloody stunning…Malcolm

Jeez, best bike doesn't even get on the list  😕 If it was there I'd vote the 1938 R51. Yeah, you could argue that the R32 was the foundation bike for all boxers and also incorporated the now traditional shaft drive – but, by 1938 the benefits of overhead cams were known; higher revs could be obtained before the onset of valve float. The basic boxer design didn’t lend itself to overhead cams so, to obtain the benefits of overhead cams without overly increasing the engine width, BMW incorporated an system very advanced for its time on its racing bikes. Must have been a pretty good system because BMW resurrected it many decades later in the R 1100 RS oilhead. The system was two cams in the head operating rocker arms via short push rods. BMW produced 3775 R51s between 1938 and 1940. The R51 had a 4 speed gearbox and the engine developed 24hp@5600rpm, not bad for a 494cc 2-cylinder overhead valve. It only weighed 182kg and got up to a pretty reasonable 140kph. I have coveted one for decades, I know one guy in New Zealand who has a minter, and he’ll not sell it. The last one I heard of at auction in the UK went for close to the equivalent of NZ$21,000