I personally use King British and JMC catfish pellets when it comes to pellets for corys (both of which brands they enjoy thoroughly, but they seem to prefer the JMC ones slightly more since they are larger), they are almost always eaten before they fully disintegrate by the corys though so i don't know how long they'd usually take to fully disintegrate (i'm estimating about 5mins+).
Never tried the Omega or Hbh ones though so can't help you there.