I am going to vote for Money Inc here.
Do I need to remind everyone that Hogan and Savage as "The Mega Powers" were, once again, not a "legit" tag team? They existed for two reasons - they gave Summer Slam a viable Main Event (Mega Powers vs Mega Bucks) without giving away Hogan / Andre or Savage / DiBiase outside of WrestleMania, and it made the WrestleMania 5 storyline "The Mega Powers Explode" more legs to stand on.
Aside from that, The Mega Powers were devoid of longevity or legitimacy, and existed only to advance singles storylines. They never went for titles, and outside of that one night at SummerSlam, hardly ever teamed up at all.
Money Inc, however, was the perfect marriage of two single wrestlers gimmicks into a re-birth for both men. Rotundo and DiBiase were advancing in age, and DiBiase's main event days were long behind him. This gimmick gave them the perfect heel heat, and as ring technicians, few were better.
Don't be blinded by the Mega Power's star power. They wrestled one match that meant anything. Outside of that, they were just a pair of egos leading a company. And if you combat me with them teaming up in the "Triple Tiered Cage" against "The Alliance to End Hulkamania," I will E-Slap you.