CC used to be pretty useful but then they stopped letting us sleep mobs and generally speedruns fell out of style. Silence and stun are both still good for getting rid of giant AOEs or preventing long casts (like Banish 3). Knockback is generally just an annoyance now since you only see it with Garuda or Fluid Aura being used on trash you're going to kill anyway. Heavy and Slow are largely useless though Slow has a bit more use than Heavy. The only real place you'll see CC utilized is in raids, and only in specific instances (orb phase of Brawler, heart in A7S, orbs again in A8S, other stuff from previous tiers).