Comic Wolverine has received (and lost, and regained and ad nauseam) boosts to his healing factor and adamantium lacing to his skeletal structure though not as complete as Wolverine's (Typically the joints and ligaments are not covered). Various retcons over decades of writing, Sabretooth is generally considered to always be an equal match to Logan, neither having the upper hand aside from moral differences.
The same can be said for 19999 MCU Sabretooth. Origins (which mind you, may or may not be canon anymore due to the events of Days of Future Past) shows Sabretooth and Logan equally matched.
There are four logical, practical reasons Stryker would want Wolverine for the project over Sabretooth.
- Adamantium is rare and in limited supply. Wolverine has an overall lower stature and body mass. In the movie, then entire reserve of adamantium for the procedure is used (a continuity error with X1-X3). Smaller size, less adamantium needed, more adamantium to use for Weapon XI.
- The bonding process is considered highly risky. There is a significant chance of death. Why risk losing a useful asset like Sabretooth when you can use some schmuck that deserted you instead?
- He believed, rightly, that he could trick Wolverine into the experiment.
- Risk Management. Sabretooth is a basically an amoral mercenary willing to kidnap and murder other mutants, and Striker is not a complete idiot. He knows that Sabretooth will betray him if given a reason to, so no need to make him essentially invincible. Again, see 3. (Bonus, Creed already showed signs of instability at the start of the movie, not following orders)
Note, the movie does have Sabretooth angry with Stryker, demanding the Adamantium because they had a deal. Stryker says that the tests came back, and that Sabretooth would never survive the procedure. As to why or if its the truth is not known. Kayla (Silver-Fox) also says that Stryker is using them, as he also hasn't held up his end of the deal to release her sister, right after Stryker tells Victor he wouldn't survive.
