In a purely physical matchup? Manhunter. It's been established that Despero's TP is far stronger than anything J'onn could put out.

With his Fernus feats added, I see it being a closer matchup, but ultimately Despero on top.

Despero. He is overall a better team buster telepath than MMH.

Fernus

Despero destroys J'onn's mind again

Despero was powerful enough to telepathically beat Aquaman and Martian Manhunter at the same time ...

and strong enough to physically stomp the JLAs heaviest hitters ...

however, Fernus telepathically and physically stomped the Justice League ...

and 80 White Martians ...

in less time and with less effort than Despero ... Jonn has been able to beat Despero on his own ...

Fernus would stomp Despero for that ...

@ancient_0f_days: J'onn beat him with a Ex Machina through, one that he can't do again here.

Also, Despero has mentally controlled almost all of the JLA in the midst of combat, which I consider more powerful than simply dominating someone's mind and leaving them there. It arguably takes more skill to control someone's actions completely, rather than rendering them immobile.

@ancient_0f_days: Despero is > MMH in TP. For his Super Saiyan version also we know he can still be TPbusted because White Martians have always been fooled by MMH. He is just flat out better than them.

Fernus.

Despero.

Despero obliterates.

Despero.

Despero, Fernus didn't do anything J'onn couldn't do and was in fact telepathically subdued by J'onn in the end.

Despero