I had a few X-Factors and neither the Crux nor anything in the Hyroad line will act like the X-Factor.  Nothing in the current line is very close to it, it had a medium RG and a very high differential.  The Crux Pearl would technically be the closest, although the cover is stronger than Accu Tread, followed by the IQ Tour Fusion with a similar strength coverstock though both lower RG and differential, then the Rocket, which may actually be the closest with nearly identical RGs though a lower differential, though I feel the reaction shape is different.  The Rocket is extremely clean through the fronts, with a very clean backend transition.  The X-Factor still had good length and a strong backend, but it was more of a strong arc.  Honestly the Marvel Pearl was the closest in terms of similar reaction shapes, but it has been discontinued. 

Overall hook potential is either the IQ Fusion or Rocket, reaction shape is the Crux Pearl.  I favor reaction shape over hook potential if it's close, so if I were looking for an X-Factor replacement, I would choose the Crux Pearl.  It's a lot cleaner through the fronts and sharper on the back than I think people are expecting it to be. 

If they're snappy, I'd avoid the Rocket.  It's already extremely clean on the backend, it's going to be much sharper.  I'd almost still suggest the Crux Pearl and go with a bigger VAL angle.  Something like 40x5x60 to minimize the flare and even the reaction out.  Mine is more aggressive than the Rocket, but it's smoother overall.  Rocket is very clean and sharp downlane, and while the Crux Pearl is still sharp and clean, it rolls heavier and is much smoother.