Kujo Jotaro FRA.
SP has superior speed, precision and power, so KC blitzing him is a tall order. There is also the fact that Jotaro holds a massive advantage in both scenarios whether or not both have knowledge.
One thing people has to understand is that Epitaph is an active ability, not a passive one. When and where Diavolo uses it is very important, and deactivates every time after a Time Erasure period has ended. Evidence is after Diavolo used KC on Buccielatti, he was unable to foresee Buc using the zipper to escape, or how he was unable to foresee Polnareff slicing his hand right after Time Erasure. It also only allows Diavolo to see one future at a time, meaning if Jotaro reacts to Diavolo's changed movements, Diavolo would not be able to foresee the alternate future that has been created.
With that being said, an active Epitaph wouldn't make much of a difference, as I will explain how every scenario would play out, even if Diavolo is to foresee the future.
WIthout knowledge:
In character Jotaro doesn't spam time stop, but uses it at crucial moments. The moment Diavolo skips time first and goes behind jotaro to ambush him, Jotaro's awareness and Star Platinum's higher speed and precision allows him to stop time immediately, look around, see Diavolo behind him and then oraoraoraora. Diavolo has retired.
If Jotaro stops time faster than Diavolo, he uses 3-4 seconds to cover the 10 meter distance, and the remaining time to ora ora ora ora. Diavolo has retired
Both with knowledge:
Jotaro uses the blood drop method to only stop time after Diavolo uses King Crimson.
Diavolo only has two options in this case:
1) Use King Crimson, splash blood in Jotaro's eye and ambush him from behind.
2) Use King Crimson, try to get as far away as possible from Jotaro during Time Erasure.
Case 1: Blood blinding does not work on Jotaro as shown with the finale of Part 3 fight. So as usual, SP stops time, turns around to see KC and oraoraoraoraora. Diavolo has retired.
Case 2: Diavolo uses KC, runs away for the next 10 seconds.
Case 2:
Two options-
1) Jotaro uses time stop to chase Diavolo. If Diavolo didn't run far enough, oraoraoraora. If Diavolo runs too far, Jotaro chases half the distance between them. In this case, Diavolo would need to use Time erasure to either run further away or to use it to ambush him. If Diavolo keeps using time erasure to run, Jotaro just keeps chasing until his Joestar physicals outrun Diavolo's stamina, and oraoraora. If Diavolo chooses to ambush Jotaro, he has to spend at least 5 seconds to cover the half distance between Jotaro and him, and by the time Time erasure is over, Jotaro's time stop would have completed its cooldown and can be used right away to stop time and ora ora ora diavolo.
2) Jotaro stops time, and throws projectiles he can find in the mansion, many at once, towards diavolo at high speed and precision. Diavolo is unable to react to it due to all of them behind thrown in stopped time, and his Time erasure would be on cooldown since he finished using it right before Jotaro stopped time. Diavolo gets heavily damaged, Jotaro chases him down and oraoraoraora. Diavolo retires.
The only advantage I can perceive for Diavolo is if he foresees Jotaro's mistimed time stop (which is hard since Jotaro is very precise with his timestops) and skips time to right after Jotaro stopped time so that Jotaro's timestop is on cooldown. However, even then Jotaro's Star Platinum superior physical stats would still mean that it is very likely to defend Jotaro from KC's attack from behind. One good example is how Jotaro tanked an entire barrage from The World after DIO sucked Joseph's blood with only broken bones (very likely guarded by Star Platinum). There also multiple feats of Star Platinum guarding Jotaro even when Jotaro was ambushed. After SP guards Jotaro against KC, KC loses its attack opportunity and is once again back at a disadvantage.
Honestly, Jotaro wins Diavolo in pretty much any scenario. Diavolo has very few chances of defeating Jotaro due to Star Platinum's superior stats to King Crimson, inability to attack during Time Erasure while Time stop on the other hand allows killing to be done within it. Combine this with Jotaro's calm and tactical mind, and Diavolo has almost no options of winning.
Jotaro wins this 9/10.