I think Zeno is overated....if Chrollo didnt want his ability, he wouldve killed him. Even without prep.
Well Zeno is compared to Netero & he himself said that they are like Yin & Yang but Netero is slightly stronger.
Also Chrollo asked this very same question to Zeno: "Who would win between us if it was a 1 v 1?"
Zeno said it would be himself but unsure if Chrollo would focus on not stealing his Ability & aim for the kill
So they are clearly very close
Among those 5 i mentioned, i believe that Chrollo is weakest when met randomly but strongest when prepared due to nature of his Ability, in other words, all other 4 (Hisoka, Zeno, Silva, Ging) seem to be slightly stronger than him but when Chrollo prepares before fighting & brings the Abilities he needs, he can defeat any of them
On the other hand, i believe Ging is the best Nen User among them while Hisoka have best Potential & X Factor (As mentioned in Databook), and Silva is strongest in raw power while Zeno is best in experience. So basically all 5 are same Level imo & the winner among them comes to Potential vs Nen Mastery vs Experience vs Raw Power vs X Factor
Plus you forgot Maha, who is even above Netero. Netero's hype is being close to Maha to strength. So Id say Prime Maha is Top 1 for the humans.....ofcourse discounting Future Gon and Killua.
Yeah i know, i do rank Maha above Netero however i only wanted to talk about Fully Introduced Characters
After all, we still have Beyond Netero, Don Freecs, Maha Zoldyck, Other Hunters from Netero's Generation mentioned before, Ziggs Zoldyck (Who could be Maha actually if retconned) .... etc