...there are FOUR POSSIBLE MAIN CONFIGURATIONS of ending (though this is ignoring the other test subjects, so just the climax/final trials)
A. Worst scenario. CANON ONE. Amanda shoots Lynn. Jeff shoots Amanda, and Amanda fails her test. Jeff chooses not to forgive John, kills him, and John reveals in his tape that he never finds his daughter.
B. Amanda LETS LYNN GO (ignoring the letter blackmail). Amanda passes her test. Jeff chooses NOT TO FORGIVE John anyways, kills him, and John reveals in his tape that he never finds his daughter. But hey, at least Jeff's with his wife. GOOD LUCK FINDING YOUR DAUGHTER, DENLON HOUSEHOLD. Oh, with John dead, Amanda will definitely go rogue.
C. Amanda SHOOTS LYNN. Jeff shoots Amanda, and Amanda fails her test. But this time, Jeff chooses to FORGIVE JOHN, and he reveals where his daughter's location is. Lynn either bleeds out/dies from her wounds. But silver lining, Jeff gets her daughter back.
D. Best case scenario. GOOD ENDING of John's game. Hypothetical IF everyone had kept collected. Amanda LETS LYNN GO. Amanda passes her test. Jeff chooses to FORGIVE JOHN, and he reveals where his daughter's location is. Jeff and Lynn seek their daughter. Family reunion. John and Amanda seek out to escape for another day, John's recent brain operation from Lynn, buys him SOME MORE time to say his final goodbyes, and leave Amanda as his stable passed-her-trials successor.
Again, this isn't even factoring the other test subjects LOL. Jeff could've chosen the 'forgive John' and Amanda picks the 'spares Lynn' option, BUT SAMF Jeff still failed to save the lady from the locker room, judge at the pig vat, and the guy from the Rack. HAHAHAHAHA
OR there's a version where he saved all three, but still got the worst ending cause Lynn dies, Amanda dies, John dies, and Jeff's daughter's location is taken to John's grave. And Jeff is now in a random factory room with a naked lady, a gut-covered judge, and a guy with some twisted limbs.
LOL. NOT TO MENTION THE EXACT CIRCUMSTANCES. Maybe Jeff shots Amanda non-fatally. Or Lynn's collar DETONATES EARLY, the final 'test' never comes to fruition, Jeff enters the final level with his wife's mangled corpse, a dead flatlined patient, and a frantic panicking lady.
Okay, I want a SAW III: CHOOSE YOUR FATE (like the Final Destination 3 DVD feature where you pick who lives/dies).