Four-stroke non-Hondas:
The shaft-driven Suzy 750-4 of the early 1980s (was it a GS750?) that resembled the CB750, but with a chain. Although it had more HP than the CB, it was slower, due to drive train losses and weights. Nice scooter, though.
Another, briefly, but not anymore desire: the BMW 750-3 inline of the later 1980s. The water cooling finally made me change my mind. I'm a snob: bikes should be air-cooled... (no fights, please, I'm just an opinionated old snot about this point.
).
Two-strokes:
The Suzy 380cc triple of the 1972-1974 genre. It had a 5-speed tranny then, was as nimble as the 350F but slightly bigger for comfort, would hit 80 MPH in seconds, smooth, quiet, low maintenance, cheap ($700 out the door!) and got 60 MPG. It would also run to redline in top gear at 95 MPH and hold that all day without breaking a sweat. The top end could be completely rebuilt in less than 3 hours, in the frame. A sweet, well thought-out design that was just too small for most folks, so it never did well in the U.S., better in Japan. It didn't smoke, either, due to Suzy's unique crankcase,cleaning checkvalve system and oil injection. Most non-riders never realized it was a stroker.
But, none of the above changed motorcycling forever, nor did they gather a 3rd-party support system, nor did they sell even a small fraction of the CB750 numbers....so, they are all gone!