I think that B would be a lock to take it to either the Mad Titan or Doom just from a power, knowledge and resources aspect alone. The wielder of the Power Cosmic, THE Sorcerer Supreme, the Strongest One There Is and the King of Atlantis. Squad A? I think they could defeat the villains too but it wouldn't be without significantly more effort than B. Honestly, power wise they only have Hulk and in terms of intellect you have Cap's experience and BP's genius. BP and Cap are the X factors really. They have the leadership skills and determination to pull off a win but again, this is Doom and Thanos we are talking about. I would put a bit more faith in the disfunctional Defenders over a squad of pro Avengers given these two line ups given no other context.