All three of these lenses are older designs from almost thirty years ago at the infancy of the autofocus era that gave birth to the Canon EOS platform. With lenses in the same basic class that are this old, the condition of each individual copy is probably more impactful than the differences between each lens design on paper.
The difference today between specific copies of any of these lenses is likely to be more related to the condition of the lens and how well it has remained optically aligned than to the differences between these lenses when they were all factory fresh and presumably in proper adjustment.
All are sharper at the shorter focal lengths and get a little softer at the longer focal lengths which is pretty typical of telephoto zoom lenses from that era.
The Canon is from 1989, a time before the invention of USM, and uses a micromotor for autofocusing. AF is fairly slow compared to more modern lenses. It was the very first 'L' lens released in the EF mount.
The Tokina, also released in 1989, is also a lens with a relatively slow-by-today's-standards micromotor for AF. It was looked at as a step below the other two in terms of optics when they were all current.
Depending on which version of the Sigma you are looking at it could have an HSM (Sigma's version of USM) driving autofocus. The optics in the later versions appear to be very close, if not the same, as the earlier versions.
All three of these lenses have been out of production long enough that repair parts are no longer available. If you can find anyone willing to even attempt to repair one, it will probably be on a "we'll have to charge you whether we can fix it or not" basis.