Chron can play a lot of roles and is obviously very good at it, but I think what sets f0rsaken apart from him is his sheer mastery of every agent he plays, the impact he brings, and that he can switch between playing all 4 roles better than any other player. Chron can switch between playing Initiator and Senti+Viper really well, but flexing to a character like omen or yoru would be really hard for him.
As for saadhak, he more just plays a lot of agents but isn't ever really high level or all that impactful on them, its more that his flexibility allows his calling, teammates and team compositions to flourish rather than being the best player at flexing.