If Jack is really done then yc1 can low-mid diff yc3
Perospero basically got the same treatment as Jack here, clearly we should stop talking about YC1, YC2, YC3 as if they correlate between different Yonko crews.
Literally the only value in using those names is to establish the placing in one crew strength wise, but the gaps within each crew, and how individuals of one crew compare with another don't translate as equivalents inbetween.
From everything we've seen so far i'm satisfied with separating the YC's in 1 bil + and those that peak at 1 bil.
Jack is more comparable to Cracker or Smoothie, or even Perospero, than he is to Katakuri, or Queen or King or Marco, which was pretty much established during the introduction of King and Queen when he was made to look like the runt of the group that get's punked and is afraid to talk back to them.