While i rate Vetorri more than most people likely do, I like Jack for 1u at + odds here. Its not a lock, i could see Vettori forcing a stand up fight which Jack doesnt excel in but i think Jack is all around legit and should be the next contender for the belt.
Jack and Vettori are two guys with a cpl of the better guillotines in the sport rn. That should be interesting if one of them exposes their neck. Vettori hasn't shown his as much recently but his is almost as nasty as Jack's, imo.