Etrigan easily I might add. Unless Apoc actually whips out his celestial tech which considering the number of practical appearances of aforementioned tech I say it's highly unlikely.
Stryfe at optimal levels should be stronger than God Cable with no technovirus to contend with and he was basically designed to step on Apoc just because he didn't live up to it didn't mean the capability wasn't there. Kind of like Hyperstorm. Massive potential and he kept Galactus fed for a good while but did he live up to his hype and capabilities no.
the fact that Cable is one of Apoc's greatest fears at full potential... It's kind of why he's got the extra metal bits inhibiting his power and stopping him from reaching full potential.
apocalypse fears mr. sinister as well, but does that mean that essex is more powerful or on par with he? and apoc has infected people much weaker than himself with the to-virus as well such as angel, so him infecting nathan with it doesn't really mean that cable is outright more powerful than him; more like he is a potential threat or can be useful. also, iirc cable cured himself from the virus at one time.