Motorcycles

I don't have first hand knowledge. I've heard the printed manuals are not great but that their online versions are good.

I've generally preferred buying the manufacturer's manual even though they're relatively expensive. Honda's manuals and their Common Service manual in particular were excellent. KTM's is just okay, disappointing after coming from Honda's and BMW's manuals, at least it gets the wiring diagram and torque specs right.

I've had mixed experience with Haynes and Clymer. They're better than nothing but the photos are not so good, they rarely cover differences between years, and make a lot of assumptions.